wrap in try-catch

Author: Rich-Harris

packages/svelte/src/compiler/phases/3-transform/client/transform-client.js

@@ -350,7 +350,7 @@ export function client_component(analysis, options) {
 	const push_args = [b.id('$$props'), b.literal(analysis.runes)];
 	if (dev) push_args.push(b.id(analysis.name));
 
-	const component_block = b.block([
+	let component_block = b.block([
 		...store_setup,
 		...legacy_reactive_declarations,
 		...group_binding_declarations,
@@ -362,10 +362,6 @@ export function client_component(analysis, options) {
 		.../** @type {ESTree.Statement[]} */ (template.body)
 	]);
 
-	if (analysis.disposable.length > 0) {
-		component_block.body.push(b.stmt(b.call('$.dispose', ...analysis.disposable)));
-	}
-
 	if (!analysis.runes) {
 		// Bind static exports to props so that people can access them with bind:x
 		for (const { name, alias } of analysis.exports) {
@@ -495,6 +491,16 @@ export function client_component(analysis, options) {
 
 	body = [...imports, ...state.module_level_snippets, ...body];
 
+	if (analysis.disposable.length > 0) {
+		component_block = b.block([
+			b.declaration(
+				'var',
+				analysis.disposable.map((id) => b.declarator(id))
+			),
+			b.try(component_block.body, null, [b.stmt(b.call('$.dispose', ...analysis.disposable))])
+		]);
+	}
+
 	const component = b.function_declaration(
 		b.id(analysis.name),
 		should_inject_props ? [b.id('$$anchor'), b.id('$$props')] : [b.id('$$anchor')],

packages/svelte/src/compiler/phases/3-transform/client/visitors/VariableDeclaration.js

@@ -351,14 +351,14 @@ export function VariableDeclaration(node, context) {
 			...node.declarations.map((declarator) => /** @type {Identifier} */ (declarator.id))
 		);
 
-		if (dev) {
-			declarations = declarations.map((declarator) => ({
-				...declarator,
-				init: b.call('$.disposable', /** @type {Expression} */ (declarator.init))
-			}));
-		}
+		const assignments = declarations.map((declarator) => {
+			let init = /** @type {Expression} */ (declarator.init);
+			if (dev) init = b.call('$.disposable', init);
+
+			return b.assignment('=', declarator.id, init);
+		});
 
-		kind = 'const';
+		return assignments.length === 1 ? assignments[0] : b.sequence(assignments);
 	}
 
 	return {

packages/svelte/src/compiler/utils/builders.js

@@ -635,6 +635,35 @@ export function throw_error(str) {
 	};
 }
 
+/**
+ * @param {ESTree.Statement[]} body
+ * @param {ESTree.CatchClause | null} handler
+ * @param {ESTree.Statement[] | null} finalizer
+ * @returns {ESTree.TryStatement}
+ */
+function try_builder(body, handler, finalizer) {
+	return {
+		type: 'TryStatement',
+		block: block(body),
+		handler,
+		finalizer: finalizer && block(finalizer)
+	};
+}
+
+/**
+ *
+ * @param {ESTree.Pattern | null} param
+ * @param {ESTree.Statement[]} body
+ * @returns {ESTree.CatchClause}
+ */
+function catch_clause(param, body) {
+	return {
+		type: 'CatchClause',
+		param,
+		body: block(body)
+	};
+}
+
 export {
 	await_builder as await,
 	let_builder as let,
@@ -648,7 +677,9 @@ export {
 	if_builder as if,
 	this_instance as this,
 	null_instance as null,
-	debugger_builder as debugger
+	debugger_builder as debugger,
+	try_builder as try,
+	catch_clause as catch
 };
 
 /**