diff --git a/packages/svelte/src/compiler/errors-tmp.js b/packages/svelte/src/compiler/errors-tmp.js
deleted file mode 100644
index bb242ada00..0000000000
--- a/packages/svelte/src/compiler/errors-tmp.js
+++ /dev/null
@@ -1,174 +0,0 @@
-/** @typedef {{ start?: number, end?: number }} NodeLike */
-/** @typedef {Record<string, (...args: any[]) => string>} Errors */
-
-/**
- * @param {Array<string | number>} items
- * @param {string} conjunction
- */
-function list(items, conjunction = 'or') {
-	if (items.length === 1) return items[0];
-	return `${items.slice(0, -1).join(', ')} ${conjunction} ${items[items.length - 1]}`;
-}
-
-/** @satisfies {Errors} */
-const internal = {
-	/** @param {string} message */
-	TODO: (message) => `TODO ${message}`,
-
-	/** @param {string} message */
-	INTERNAL: (message) =>
-		`Internal compiler error: ${message}. Please report this to https://github.com/sveltejs/svelte/issues`
-};
-
-/** @satisfies {Errors} */
-const errors = {
-	...internal
-
-	// missing_contenteditable_attribute: {
-	// 	code: 'missing-contenteditable-attribute',
-	// 	message:
-	// 		"'contenteditable' attribute is required for textContent, innerHTML and innerText two-way bindings"
-	// },
-	// textarea_duplicate_value: {
-	// 	code: 'textarea-duplicate-value',
-	// 	message:
-	// 		'A <textarea> can have either a value attribute or (equivalently) child content, but not both'
-	// },
-	// invalid_attribute_head: {
-	// 	code: 'invalid-attribute',
-	// 	message: '<svelte:head> should not have any attributes or directives'
-	// },
-	// invalid_action: {
-	// 	code: 'invalid-action',
-	// 	message: 'Actions can only be applied to DOM elements, not components'
-	// },
-	// invalid_class: {
-	// 	code: 'invalid-class',
-	// 	message: 'Classes can only be applied to DOM elements, not components'
-	// },
-	// invalid_transition: {
-	// 	code: 'invalid-transition',
-	// 	message: 'Transitions can only be applied to DOM elements, not components'
-	// },
-	// invalid_let: {
-	// 	code: 'invalid-let',
-	// 	message: 'let directive value must be an identifier or an object/array pattern'
-	// },
-	// invalid_slot_directive: {
-	// 	code: 'invalid-slot-directive',
-	// 	message: '<slot> cannot have directives'
-	// },
-	// dynamic_slot_name: {
-	// 	code: 'dynamic-slot-name',
-	// 	message: '<slot> name cannot be dynamic'
-	// },
-	// invalid_slot_attribute_value_missing: {
-	// 	code: 'invalid-slot-attribute',
-	// 	message: 'slot attribute value is missing'
-	// },
-	// illegal_structure_title: {
-	// 	code: 'illegal-structure',
-	// 	message: '<title> can only contain text and {tags}'
-	// },
-	// duplicate_transition: /**
-	//  * @param {string} directive
-	//  * @param {string} parent_directive
-	//  */ (directive, parent_directive) => {
-	// 	/** @param {string} _directive */
-	// 	function describe(_directive) {
-	// 		return _directive === 'transition' ? "a 'transition'" : `an '${_directive}'`;
-	// 	}
-	// 	const message =
-	// 		directive === parent_directive
-	// 			? `An element can only have one '${directive}' directive`
-	// 			: `An element cannot have both ${describe(parent_directive)} directive and ${describe(
-	// 					directive
-	// 			  )} directive`;
-	// 	return {
-	// 		code: 'duplicate-transition',
-	// 		message
-	// 	};
-	// },
-	// default_export: {
-	// 	code: 'default-export',
-	// 	message: 'A component cannot have a default export'
-	// },
-	// illegal_declaration: {
-	// 	code: 'illegal-declaration',
-	// 	message: 'The $ prefix is reserved, and cannot be used for variable and import names'
-	// },
-	// invalid_directive_value: {
-	// 	code: 'invalid-directive-value',
-	// 	message:
-	// 		'Can only bind to an identifier (e.g. `foo`) or a member expression (e.g. `foo.bar` or `foo[baz]`)'
-	// },
-};
-
-// interface is duplicated between here (used internally) and ./interfaces.js
-// (exposed publicly), and I'm not sure how to avoid that
-export class CompileError extends Error {
-	name = 'CompileError';
-
-	/** @type {import('#compiler').CompileError['filename']} */
-	filename = undefined;
-
-	/** @type {import('#compiler').CompileError['position']} */
-	position = undefined;
-
-	/** @type {import('#compiler').CompileError['start']} */
-	start = undefined;
-
-	/** @type {import('#compiler').CompileError['end']} */
-	end = undefined;
-
-	/**
-	 *
-	 * @param {string} code
-	 * @param {string} message
-	 * @param {[number, number] | undefined} position
-	 */
-	constructor(code, message, position) {
-		super(message);
-		this.code = code;
-		this.position = position;
-	}
-
-	toString() {
-		let out = `${this.name}: ${this.message}`;
-
-		out += `\n(${this.code})`;
-
-		if (this.filename) {
-			out += `\n${this.filename}`;
-
-			if (this.start) {
-				out += `${this.start.line}:${this.start.column}`;
-			}
-		}
-
-		return out;
-	}
-}
-
-/**
- * @template {Exclude<keyof typeof errors, 'TODO'>} T
- * @param {NodeLike | number | null} node
- * @param {T} code
- * @param  {Parameters<typeof errors[T]>} args
- * @returns {never}
- */
-export function error(node, code, ...args) {
-	const fn = errors[code];
-
-	// @ts-expect-error
-	const message = fn(...args);
-
-	const start = typeof node === 'number' ? node : node?.start;
-	const end = typeof node === 'number' ? node : node?.end;
-
-	throw new CompileError(
-		code,
-		message,
-		start !== undefined && end !== undefined ? [start, end] : undefined
-	);
-}
diff --git a/packages/svelte/src/compiler/index.js b/packages/svelte/src/compiler/index.js
index 30b623865a..eee35bf2a8 100644
--- a/packages/svelte/src/compiler/index.js
+++ b/packages/svelte/src/compiler/index.js
@@ -1,6 +1,6 @@
 import { getLocator } from 'locate-character';
 import { walk as zimmerframe_walk } from 'zimmerframe';
-import { CompileError } from './errors-tmp.js';
+import { CompileError } from './errors.js';
 import { convert } from './legacy.js';
 import { parse as parse_acorn } from './phases/1-parse/acorn.js';
 import { parse as _parse } from './phases/1-parse/index.js';
@@ -157,6 +157,6 @@ export function walk() {
 	);
 }
 
-export { CompileError } from './errors-tmp.js';
+export { CompileError } from './errors.js';
 
 export { VERSION } from '../version.js';
diff --git a/packages/svelte/src/compiler/phases/1-parse/index.js b/packages/svelte/src/compiler/phases/1-parse/index.js
index 6fd9080986..0982f4a960 100644
--- a/packages/svelte/src/compiler/phases/1-parse/index.js
+++ b/packages/svelte/src/compiler/phases/1-parse/index.js
@@ -4,7 +4,6 @@ import fragment from './state/fragment.js';
 import { regex_whitespace } from '../patterns.js';
 import { reserved } from './utils/names.js';
 import full_char_code_at from './utils/full_char_code_at.js';
-import { error } from '../../errors-tmp.js';
 import * as e from '../../errors.js';
 import { create_fragment } from './utils/create.js';
 import read_options from './read/options.js';
diff --git a/packages/svelte/src/compiler/phases/1-parse/read/context.js b/packages/svelte/src/compiler/phases/1-parse/read/context.js
index 0c4fbedab1..10cdaa44b7 100644
--- a/packages/svelte/src/compiler/phases/1-parse/read/context.js
+++ b/packages/svelte/src/compiler/phases/1-parse/read/context.js
@@ -9,7 +9,6 @@ import {
 } from '../utils/bracket.js';
 import { parse_expression_at } from '../acorn.js';
 import { regex_not_newline_characters } from '../../patterns.js';
-import { error } from '../../../errors-tmp.js';
 import * as e from '../../../errors.js';
 
 /**
diff --git a/packages/svelte/src/compiler/phases/2-analyze/index.js b/packages/svelte/src/compiler/phases/2-analyze/index.js
index 96812d0e42..10091a7105 100644
--- a/packages/svelte/src/compiler/phases/2-analyze/index.js
+++ b/packages/svelte/src/compiler/phases/2-analyze/index.js
@@ -1,6 +1,5 @@
 import is_reference from 'is-reference';
 import { walk } from 'zimmerframe';
-import { error } from '../../errors-tmp.js';
 import * as e from '../../errors.js';
 import {
 	extract_identifiers,
diff --git a/packages/svelte/src/compiler/phases/2-analyze/validation.js b/packages/svelte/src/compiler/phases/2-analyze/validation.js
index 628c932656..8d7e6348c5 100644
--- a/packages/svelte/src/compiler/phases/2-analyze/validation.js
+++ b/packages/svelte/src/compiler/phases/2-analyze/validation.js
@@ -3,7 +3,6 @@ import {
 	interactive_elements,
 	is_tag_valid_with_parent
 } from '../../../constants.js';
-import { error } from '../../errors-tmp.js';
 import * as e from '../../errors.js';
 import {
 	extract_identifiers,
@@ -367,7 +366,7 @@ const validation = {
 
 		if (node.name === 'group') {
 			if (!binding) {
-				error(node, 'INTERNAL', 'Cannot find declaration for bind:group');
+				throw new Error('Cannot find declaration for bind:group');
 			}
 		}
 
diff --git a/packages/svelte/src/compiler/phases/3-transform/client/transform-client.js b/packages/svelte/src/compiler/phases/3-transform/client/transform-client.js
index 76b726059b..4388c6849b 100644
--- a/packages/svelte/src/compiler/phases/3-transform/client/transform-client.js
+++ b/packages/svelte/src/compiler/phases/3-transform/client/transform-client.js
@@ -1,5 +1,4 @@
 import { walk } from 'zimmerframe';
-import { error } from '../../../errors-tmp.js';
 import * as b from '../../../utils/builders.js';
 import { set_scope } from '../../scope.js';
 import { template_visitors } from './visitors/template.js';
@@ -52,35 +51,41 @@ export function client_component(source, analysis, options) {
 		get before_init() {
 			/** @type {any[]} */
 			const a = [];
-			a.push = () =>
-				error(null, 'INTERNAL', 'before_init.push should not be called outside create_block');
+			a.push = () => {
+				throw new Error('before_init.push should not be called outside create_block');
+			};
 			return a;
 		},
 		get init() {
 			/** @type {any[]} */
 			const a = [];
-			a.push = () => error(null, 'INTERNAL', 'init.push should not be called outside create_block');
+			a.push = () => {
+				throw new Error('init.push should not be called outside create_block');
+			};
 			return a;
 		},
 		get update() {
 			/** @type {any[]} */
 			const a = [];
-			a.push = () =>
-				error(null, 'INTERNAL', 'update.push should not be called outside create_block');
+			a.push = () => {
+				throw new Error('update.push should not be called outside create_block');
+			};
 			return a;
 		},
 		get after_update() {
 			/** @type {any[]} */
 			const a = [];
-			a.push = () =>
-				error(null, 'INTERNAL', 'after_update.push should not be called outside create_block');
+			a.push = () => {
+				throw new Error('after_update.push should not be called outside create_block');
+			};
 			return a;
 		},
 		get template() {
 			/** @type {any[]} */
 			const a = [];
-			a.push = () =>
-				error(null, 'INTERNAL', 'template.push should not be called outside create_block');
+			a.push = () => {
+				throw new Error('template.push should not be called outside create_block');
+			};
 			return a;
 		},
 		legacy_reactive_statements: new Map(),
@@ -209,7 +214,7 @@ export function client_component(source, analysis, options) {
 	for (const [node] of analysis.reactive_statements) {
 		const statement = [...state.legacy_reactive_statements].find(([n]) => n === node);
 		if (statement === undefined) {
-			error(node, 'INTERNAL', 'Could not find reactive statement');
+			throw new Error('Could not find reactive statement');
 		}
 		instance.body.push(statement[1]);
 	}
diff --git a/packages/svelte/src/compiler/phases/3-transform/client/utils.js b/packages/svelte/src/compiler/phases/3-transform/client/utils.js
index ce385dd529..481caf6561 100644
--- a/packages/svelte/src/compiler/phases/3-transform/client/utils.js
+++ b/packages/svelte/src/compiler/phases/3-transform/client/utils.js
@@ -5,7 +5,6 @@ import {
 	is_simple_expression,
 	object
 } from '../../../utils/ast.js';
-import { error } from '../../../errors-tmp.js';
 import {
 	PROPS_IS_LAZY_INITIAL,
 	PROPS_IS_IMMUTABLE,
@@ -185,7 +184,7 @@ export function serialize_set_binding(node, context, fallback, options) {
 	}
 
 	if (assignee.type !== 'Identifier' && assignee.type !== 'MemberExpression') {
-		error(node, 'INTERNAL', `Unexpected assignment type ${assignee.type}`);
+		throw new Error(`Unexpected assignment type ${assignee.type}`);
 	}
 
 	// Handle class private/public state assignment cases
diff --git a/packages/svelte/src/compiler/phases/3-transform/client/visitors/template.js b/packages/svelte/src/compiler/phases/3-transform/client/visitors/template.js
index 4f897ba5cf..9c7706a17c 100644
--- a/packages/svelte/src/compiler/phases/3-transform/client/visitors/template.js
+++ b/packages/svelte/src/compiler/phases/3-transform/client/visitors/template.js
@@ -16,7 +16,6 @@ import {
 import { DOMProperties, PassiveEvents, VoidElements } from '../../../constants.js';
 import { is_custom_element_node, is_element_node } from '../../../nodes.js';
 import * as b from '../../../../utils/builders.js';
-import { error } from '../../../../errors-tmp.js';
 import {
 	with_loc,
 	function_visitor,
@@ -1776,10 +1775,10 @@ export const template_visitors = {
 		);
 	},
 	ClassDirective(node, { state, next }) {
-		error(node, 'INTERNAL', 'Node should have been handled elsewhere');
+		throw new Error('Node should have been handled elsewhere');
 	},
 	StyleDirective(node, { state, next }) {
-		error(node, 'INTERNAL', 'Node should have been handled elsewhere');
+		throw new Error('Node should have been handled elsewhere');
 	},
 	TransitionDirective(node, { state, visit }) {
 		let flags = node.modifiers.includes('global') ? TRANSITION_GLOBAL : 0;
@@ -2775,7 +2774,7 @@ export const template_visitors = {
 				}
 
 				default:
-					error(node, 'INTERNAL', 'unknown binding ' + node.name);
+					throw new Error('unknown binding ' + node.name);
 			}
 		}
 
diff --git a/packages/svelte/src/compiler/phases/3-transform/server/transform-server.js b/packages/svelte/src/compiler/phases/3-transform/server/transform-server.js
index 4e6a12734d..db915008c2 100644
--- a/packages/svelte/src/compiler/phases/3-transform/server/transform-server.js
+++ b/packages/svelte/src/compiler/phases/3-transform/server/transform-server.js
@@ -22,7 +22,6 @@ import {
 	transform_inspect_rune
 } from '../utils.js';
 import { create_attribute, is_custom_element_node, is_element_node } from '../../nodes.js';
-import { error } from '../../../errors-tmp.js';
 import { binding_properties } from '../../bindings.js';
 import { regex_starts_with_newline, regex_whitespaces_strict } from '../../patterns.js';
 import {
@@ -419,7 +418,7 @@ function serialize_set_binding(node, context, fallback) {
 	}
 
 	if (node.left.type !== 'Identifier' && node.left.type !== 'MemberExpression') {
-		error(node, 'INTERNAL', `Unexpected assignment type ${node.left.type}`);
+		throw new Error(`Unexpected assignment type ${node.left.type}`);
 	}
 
 	let left = node.left;
@@ -1329,10 +1328,10 @@ const template_visitors = {
 		state.template.push(block_close);
 	},
 	ClassDirective(node) {
-		error(node, 'INTERNAL', 'Node should have been handled elsewhere');
+		throw new Error('Node should have been handled elsewhere');
 	},
 	StyleDirective(node) {
-		error(node, 'INTERNAL', 'Node should have been handled elsewhere');
+		throw new Error('Node should have been handled elsewhere');
 	},
 	RegularElement(node, context) {
 		const metadata = {
@@ -2124,14 +2123,17 @@ export function server_component(analysis, options) {
 		get init() {
 			/** @type {any[]} */
 			const a = [];
-			a.push = () => error(null, 'INTERNAL', 'init.push should not be called outside create_block');
+			a.push = () => {
+				throw new Error('init.push should not be called outside create_block');
+			};
 			return a;
 		},
 		get template() {
 			/** @type {any[]} */
 			const a = [];
-			a.push = () =>
-				error(null, 'INTERNAL', 'template.push should not be called outside create_block');
+			a.push = () => {
+				throw new Error('template.push should not be called outside create_block');
+			};
 			return a;
 		},
 		metadata: {
@@ -2199,7 +2201,7 @@ export function server_component(analysis, options) {
 	for (const [node] of analysis.reactive_statements) {
 		const statement = [...state.legacy_reactive_statements].find(([n]) => n === node);
 		if (statement === undefined) {
-			error(node, 'INTERNAL', 'Could not find reactive statement');
+			throw new Error('Could not find reactive statement');
 		}
 
 		if (
diff --git a/packages/svelte/src/compiler/phases/scope.js b/packages/svelte/src/compiler/phases/scope.js
index 4636e98fd8..d815ff88fd 100644
--- a/packages/svelte/src/compiler/phases/scope.js
+++ b/packages/svelte/src/compiler/phases/scope.js
@@ -2,7 +2,6 @@ import is_reference from 'is-reference';
 import { walk } from 'zimmerframe';
 import { is_element_node } from './nodes.js';
 import * as b from '../utils/builders.js';
-import { error } from '../errors-tmp.js';
 import * as e from '../errors.js';
 import { extract_identifiers, extract_identifiers_from_destructuring } from '../utils/ast.js';
 import { JsKeywords, Runes } from './constants.js';
@@ -167,7 +166,7 @@ export class Scope {
 	get_bindings(node) {
 		const bindings = this.declarators.get(node);
 		if (!bindings) {
-			error(node, 'INTERNAL', 'No binding found for declarator');
+			throw new Error('No binding found for declarator');
 		}
 		return bindings;
 	}
diff --git a/packages/svelte/src/compiler/utils/assert.js b/packages/svelte/src/compiler/utils/assert.js
index 303f508553..b6dc6bf90c 100644
--- a/packages/svelte/src/compiler/utils/assert.js
+++ b/packages/svelte/src/compiler/utils/assert.js
@@ -1,12 +1,10 @@
-import { error } from '../errors-tmp.js';
-
 /**
  * @template T
  * @param {T} value
  * @returns {asserts value is NonNullable<T>}
  */
 export function ok(value) {
-	if (!value) error(null, 'INTERNAL', 'Assertion failed');
+	if (!value) throw new Error('Assertion failed');
 }
 
 /**
@@ -16,5 +14,5 @@ export function ok(value) {
  * @returns {asserts actual is T}
  */
 export function equal(actual, expected) {
-	if (actual !== expected) error(null, 'INTERNAL', 'Assertion failed');
+	if (actual !== expected) throw new Error('Assertion failed');
 }
diff --git a/packages/svelte/src/compiler/validate-options.js b/packages/svelte/src/compiler/validate-options.js
index d8a4a67f91..d9b0e9b1c3 100644
--- a/packages/svelte/src/compiler/validate-options.js
+++ b/packages/svelte/src/compiler/validate-options.js
@@ -1,4 +1,3 @@
-import { error } from './errors-tmp.js';
 import * as e from './errors.js';
 
 /**