fix: ensure <svelte:boundary> properly removes error content in production mode (#15793)

* fix: ensure <svelte:boundary> properly removes error content in production mode * add changeset

Author: zeroberry

.changeset/eleven-roses-speak.md

@@ -0,0 +1,5 @@
+---
+'svelte': patch
+---
+
+fix: ensure <svelte:boundary> properly removes error content in production mode

packages/svelte/src/internal/client/runtime.js

@@ -291,67 +291,58 @@ export function handle_error(error, effect, previous_effect, component_context)
 is_throwing_error = true;
 }
 
-if (
-!DEV ||
-component_context === null ||
-!(error instanceof Error) ||
-handled_errors.has(error)
-) {
-propagate_error(error, effect);
-return;
-}
-
-handled_errors.add(error);
+if (DEV && component_context !== null && error instanceof Error && !handled_errors.has(error)) {
+handled_errors.add(error);
 
-const component_stack = [];
+const component_stack = [];
 
-const effect_name = effect.fn?.name;
+const effect_name = effect.fn?.name;
 
-if (effect_name) {
-component_stack.push(effect_name);
-}
+if (effect_name) {
+component_stack.push(effect_name);
+}
 
-/** @type {ComponentContext | null} */
-let current_context = component_context;
+/** @type {ComponentContext | null} */
+let current_context = component_context;
 
-while (current_context !== null) {
-if (DEV) {
+while (current_context !== null) {
 /** @type {string} */
 var filename = current_context.function?.[FILENAME];
 
 if (filename) {
 const file = filename.split('/').pop();
 component_stack.push(file);
 }
+
+current_context = current_context.p;
 }
 
-current_context = current_context.p;
-}
+const indent = is_firefox ? ' ' : '\t';
+define_property(error, 'message', {
+value:
+error.message + `\n${component_stack.map((name) => `\n${indent}in ${name}`).join('')}\n`
+});
+define_property(error, 'component_stack', {
+value: component_stack
+});
 
-const indent = is_firefox ? ' ' : '\t';
-define_property(error, 'message', {
-value: error.message + `\n${component_stack.map((name) => `\n${indent}in ${name}`).join('')}\n`
-});
-define_property(error, 'component_stack', {
-value: component_stack
-});
-
-const stack = error.stack;
-
-// Filter out internal files from callstack
-if (stack) {
-const lines = stack.split('\n');
-const new_lines = [];
-for (let i = 0; i < lines.length; i++) {
-const line = lines[i];
-if (line.includes('svelte/src/internal')) {
-continue;
+const stack = error.stack;
+
+// Filter out internal files from callstack
+if (stack) {
+const lines = stack.split('\n');
+const new_lines = [];
+for (let i = 0; i < lines.length; i++) {
+const line = lines[i];
+if (line.includes('svelte/src/internal')) {
+continue;
+}
+new_lines.push(line);
 }
-new_lines.push(line);
+define_property(error, 'stack', {
+value: new_lines.join('\n')
+});
 }
-define_property(error, 'stack', {
-value: new_lines.join('\n')
-});
 }
 
 propagate_error(error, effect);

packages/svelte/tests/runtime-runes/samples/error-boundary-22/Child.svelte

@@ -0,0 +1,3 @@
+<script>
+throw new Error();
+</script>

packages/svelte/tests/runtime-runes/samples/error-boundary-22/_config.js

@@ -0,0 +1,11 @@
+import { flushSync } from 'svelte';
+import { test } from '../../test';
+
+export default test({
+mode: ['client'],
+test({ assert, target }) {
+flushSync();
+
+assert.htmlEqual(target.innerHTML, '<p>error occurred</p>');
+}
+});

packages/svelte/tests/runtime-runes/samples/error-boundary-22/main.svelte

@@ -0,0 +1,15 @@
+<script>
+import Child from "./Child.svelte"
+</script>
+
+<svelte:boundary>
+<p>This should be removed</p>
+
+{#if true}
+<Child />
+{/if}
+
+{#snippet failed()}
+<p>error occurred</p>
+{/snippet}
+</svelte:boundary>