fix error

Author: Rich-Harris

documentation/docs/98-reference/.generated/compile-errors.md

@@ -762,6 +762,12 @@ A component can have a single top-level `<style>` element
 `<svelte:body>` does not support non-event attributes or spread attributes
 ```
 
+### svelte_boundary_invalid_attribute
+
+```
+Valid attributes on `<svelte:boundary>` are `onerror` and `failed`
+```
+
 ### svelte_component_invalid_this
 
 ```

packages/svelte/messages/compile-errors/template.md

@@ -282,6 +282,10 @@ HTML restricts where certain elements can appear. In case of a violation the bro
 
 > `<svelte:body>` does not support non-event attributes or spread attributes
 
+## svelte_boundary_invalid_attribute
+
+> Valid attributes on `<svelte:boundary>` are `onerror` and `failed`
+
 ## svelte_component_invalid_this
 
 > Invalid component definition — must be an `{expression}`

packages/svelte/src/compiler/errors.js

@@ -1508,4 +1508,13 @@ export function unexpected_reserved_word(node, word) {
  */
 export function void_element_invalid_content(node) {
 	e(node, "void_element_invalid_content", "Void elements cannot have children or closing tags");
+}
+
+/**
+ * Valid attributes on `<svelte:boundary>` are `onerror` and `failed`
+ * @param {null | number | NodeLike} node
+ * @returns {never}
+ */
+export function svelte_boundary_invalid_attribute(node) {
+	e(node, "svelte_boundary_invalid_attribute", "Valid attributes on `<svelte:boundary>` are `onerror` and `failed`");
 }

packages/svelte/src/compiler/phases/2-analyze/visitors/SvelteBoundary.js

@@ -2,14 +2,16 @@
 /** @import { Context } from '../types' */
 import * as e from '../../../errors.js';
 
+const valid = ['onerror', 'failed'];
+
 /**
  * @param {AST.SvelteBoundary} node
  * @param {Context} context
  */
 export function SvelteBoundary(node, context) {
 	for (const attribute of node.attributes) {
-		if (attribute.type !== 'Attribute') {
-			e.illegal_element_attribute(attribute, 'svelte:boundary');
+		if (attribute.type !== 'Attribute' || !valid.includes(attribute.name)) {
+			e.svelte_boundary_invalid_attribute(attribute);
 		}
 	}