From f5ae2634d3c1099b78751ddd22ae052abf4fdb10 Mon Sep 17 00:00:00 2001
From: Rich Harris <rich.harris@vercel.com>
Date: Wed, 16 Jul 2025 16:49:13 -0400
Subject: [PATCH] remove dev_effect_stack stuff, it's not very helpful

---
 .../src/internal/client/reactivity/batch.js   | 34 +------------------
 .../svelte/src/internal/client/runtime.js     | 12 +------
 2 files changed, 2 insertions(+), 44 deletions(-)

diff --git a/packages/svelte/src/internal/client/reactivity/batch.js b/packages/svelte/src/internal/client/reactivity/batch.js
index 91f9c547db..11eec82e4d 100644
--- a/packages/svelte/src/internal/client/reactivity/batch.js
+++ b/packages/svelte/src/internal/client/reactivity/batch.js
@@ -46,9 +46,6 @@ export let current_batch = null;
  */
 export let batch_deriveds = null;
 
-/** @type {Effect[]} Stack of effects, dev only */
-export let dev_effect_stack = [];
-
 /** @type {Set<() => void>} */
 export let effect_pending_updates = new Set();
 
@@ -378,9 +375,6 @@ export class Batch {
 			set_is_updating_effect(was_updating_effect);
 
 			last_scheduled_effect = null;
-			if (DEV) {
-				dev_effect_stack = [];
-			}
 		}
 	}
 
@@ -493,10 +487,6 @@ export function flushSync(fn) {
 			// we need to reset it here as well in case the first time there's 0 queued root effects
 			last_scheduled_effect = null;
 
-			if (DEV) {
-				dev_effect_stack = [];
-			}
-
 			return /** @type {T} */ (result);
 		}
 
@@ -504,15 +494,6 @@ export function flushSync(fn) {
 	}
 }
 
-function log_effect_stack() {
-	// eslint-disable-next-line no-console
-	console.error(
-		'Last ten effects were: ',
-		dev_effect_stack.slice(-10).map((d) => d.fn)
-	);
-	dev_effect_stack = [];
-}
-
 function infinite_loop_guard() {
 	try {
 		e.effect_update_depth_exceeded();
@@ -526,21 +507,8 @@ function infinite_loop_guard() {
 		// Try and handle the error so it can be caught at a boundary, that's
 		// if there's an effect available from when it was last scheduled
 		if (last_scheduled_effect !== null) {
-			if (DEV) {
-				try {
-					invoke_error_boundary(error, last_scheduled_effect);
-				} catch (e) {
-					// Only log the effect stack if the error is re-thrown
-					log_effect_stack();
-					throw e;
-				}
-			} else {
-				invoke_error_boundary(error, last_scheduled_effect);
-			}
+			invoke_error_boundary(error, last_scheduled_effect);
 		} else {
-			if (DEV) {
-				log_effect_stack();
-			}
 			throw error;
 		}
 	}
diff --git a/packages/svelte/src/internal/client/runtime.js b/packages/svelte/src/internal/client/runtime.js
index 6c4d92bbad..306b9b9dd9 100644
--- a/packages/svelte/src/internal/client/runtime.js
+++ b/packages/svelte/src/internal/client/runtime.js
@@ -42,13 +42,7 @@ import {
 	set_dev_stack
 } from './context.js';
 import * as w from './warnings.js';
-import {
-	Batch,
-	batch_deriveds,
-	dev_effect_stack,
-	flushSync,
-	schedule_effect
-} from './reactivity/batch.js';
+import { Batch, batch_deriveds, flushSync, schedule_effect } from './reactivity/batch.js';
 import { handle_error } from './error-handling.js';
 import { UNINITIALIZED } from '../../constants.js';
 
@@ -491,10 +485,6 @@ export function update_effect(effect) {
 				}
 			}
 		}
-
-		if (DEV) {
-			dev_effect_stack.push(effect);
-		}
 	} finally {
 		is_updating_effect = was_updating_effect;
 		active_effect = previous_effect;