Make checking for DestructuedVariable a one-liner

src/compiler/compile/nodes/EachBlock.ts

@@ -45,9 +45,8 @@ export default class EachBlock extends AbstractBlock {
 		unpack_destructuring({ contexts: this.contexts, node: info.context, scope, component, owner: this, context_rest_properties: this.context_rest_properties });
 
 		this.contexts.forEach(context => {
-			if (context.type === 'DestructuredVariable') {
-				this.scope.add(context.key.name, this.expression.dependencies, this);
-			}
+			if (context.type !== 'DestructuredVariable') return;
+			this.scope.add(context.key.name, this.expression.dependencies, this);
 		});
 
 		if (this.index) {

src/compiler/compile/nodes/shared/Context.ts

@@ -214,11 +214,10 @@ function update_reference(
 	const find_from_context = (node: Identifier) => {
 		for (let i = n; i < contexts.length; i++) {
 			const cur_context = contexts[i];
-			if (cur_context.type === 'DestructuredVariable') {
-				const { key } = cur_context;
-				if (node.name === key.name) {
-					throw new Error(`Cannot access '${node.name}' before initialization`);
-				}
+			if (cur_context.type !== 'DestructuredVariable') continue; 
+			const { key } = cur_context;
+			if (node.name === key.name) {
+				throw new Error(`Cannot access '${node.name}' before initialization`);
 			}
 		}
 		return to_ctx(node.name);

src/compiler/compile/render_dom/wrappers/AwaitBlock.ts

@@ -70,9 +70,8 @@ class AwaitBlockBranch extends Wrapper {
 			this.renderer.add_to_context(this.value, true);
 		} else {
 			contexts.forEach(context => {
-				if (context.type === 'DestructuredVariable') {
-					this.renderer.add_to_context(context.key.name, true);
-				}
+				if (context.type !== 'DestructuredVariable') return;
+				this.renderer.add_to_context(context.key.name, true);
 			});
 			this.value = this.block.parent.get_unique_name('value').name;
 			this.value_contexts = contexts;