fix

Author: Rich-Harris

eslint.config.js

@@ -49,12 +49,13 @@ export default [
 		},
 		rules: {
 			'@typescript-eslint/await-thenable': 'error',
-			'@typescript-eslint/prefer-promise-reject-errors': 'error',
 			'@typescript-eslint/require-await': 'error',
 			'no-console': 'error',
 			'lube/svelte-naming-convention': ['error', { fixSameNames: true }],
 			// eslint isn't that well-versed with JSDoc to know that `foo: /** @type{..} */ (foo)` isn't a violation of this rule, so turn it off
 			'object-shorthand': 'off',
+			// eslint is being a dummy here too
+			'@typescript-eslint/prefer-promise-reject-errors': 'off',
 			'no-var': 'off',
 
 			// TODO: enable these rules and run `pnpm lint:fix`

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

@@ -1,25 +1,33 @@
 /** @import { AwaitExpression, Expression, Property, SpreadElement } from 'estree' */
 /** @import { Context } from '../types' */
-import { dev } from '../../../../state.js';
+import { dev, is_ignored } from '../../../../state.js';
 import * as b from '../../../../utils/builders.js';
 
 /**
  * @param {AwaitExpression} node
  * @param {Context} context
  */
 export function AwaitExpression(node, context) {
-	const save =
-		// preserve context if this is a top-level await in `<script>`
-		(context.state.is_instance && context.state.scope.function_depth === 1) ||
-		// or if this is a derived/template expression
-		(is_reactive_expression(context) && !is_last_evaluated_expression(context, node));
-
-	if (dev || save) {
-		const expression = /** @type {Expression} */ (context.visit(node.argument));
-		return b.call(b.await(b.call('$.save', expression, !save && b.false)));
+	const argument = /** @type {Expression} */ (context.visit(node.argument));
+
+	const tla = context.state.is_instance && context.state.scope.function_depth === 1;
+
+	// preserve context for
+	//   a) top-level await and
+	//   b) awaits that precede other expressions in template or `$derived(...)`
+	if (tla || is_reactive_expression(context)) {
+		if (tla || !is_last_evaluated_expression(context, node)) {
+			return b.call(b.await(b.call('$.save', argument)));
+		}
+	}
+
+	// in dev, note which values are read inside a reactive expression,
+	// but don't track them
+	else if (dev && !is_ignored(node, 'await_reactivity_loss')) {
+		return b.call(b.await(b.call('$.save', argument, b.false)));
 	}
 
-	return context.next();
+	return argument === node.argument ? node : { ...node, argument };
 }
 
 /**

packages/svelte/src/internal/client/reactivity/deriveds.js

@@ -116,7 +116,13 @@ export function async_derived(fn, location) {
 
 	render_effect(() => {
 		if (DEV) from_async_derived = active_effect;
-		var p = fn();
+
+		try {
+			var p = fn();
+		} catch (error) {
+			p = Promise.reject(error);
+		}
+
 		if (DEV) from_async_derived = null;
 
 		promise =