prevent await blocks using stale state - fixes #1131

src/generators/nodes/AwaitBlock.ts

@@ -127,8 +127,10 @@ export default class AwaitBlock extends Node {
 
 				if (@isPromise(${promise})) {
 					${promise}.then(function(${value}) {
+						var state = #component.get();
 						${replace_await_block}(${token}, ${create_then_block}, ${value}, ${params});
 					}, function (${error}) {
+						var state = #component.get();
 						${replace_await_block}(${token}, ${create_catch_block}, ${error}, ${params});
 					});
 

test/runtime/samples/await-set-simultaneous/_config.js

@@ -0,0 +1,16 @@
+export default {
+	test(assert, component, target) {
+		const promise = Promise.resolve().then(() => component.set({ answer: 42 }));
+
+		component.set({ promise });
+
+		assert.htmlEqual(target.innerHTML, `<p>wait for it...</p>`);
+
+		return promise
+			.then(() => {
+				assert.htmlEqual(target.innerHTML, `
+					<p>the answer is 42!</p>
+				`);
+			});
+	}
+};

test/runtime/samples/await-set-simultaneous/main.html

@@ -0,0 +1,9 @@
+{{#if promise}}
+	{{#await promise}}
+		<p>wait for it...</p>
+	{{then _}}
+		<p>the answer is {{answer}}!</p>
+	{{catch error}}
+		<p>well that's odd</p>
+	{{/await}}
+{{/if}}