[wrangler] Keep request-scoped proxy errors non-fatal

.changeset/tidy-pandas-smile.md

@@ -0,0 +1,5 @@
+---
+"wrangler": patch
+---
+
+Keep the local development server running when proxying an individual request fails.

packages/wrangler/src/__tests__/api/startDevWorker/ProxyController.test.ts

@@ -4,7 +4,28 @@ import { FakeBus } from "../../helpers/fake-bus";
 import { mockConsoleMethods } from "../../helpers/mock-console";
 
 describe("ProxyController", () => {
-	mockConsoleMethods();
+	const std = mockConsoleMethods();
+
+	test("request-scoped ProxyWorker errors are logged without stopping dev", ({
+		expect,
+	}) => {
+		const bus = new FakeBus();
+		const controller = new ProxyController(bus);
+
+		controller.onProxyWorkerMessage({
+			type: "error",
+			error: {
+				name: "Error",
+				message: "Network connection lost.",
+				stack: "Error: Network connection lost.",
+			},
+		});
+
+		expect(bus.events).toEqual([]);
+		expect(std.err).toContain(
+			"Error proxying request to the local Worker: Network connection lost."
+		);
+	});
 
 	test("Runtime.exceptionThrown dispatches a typed runtimeError event", async ({
 		expect,

packages/wrangler/src/api/startDevWorker/ProxyController.ts

@@ -475,7 +475,10 @@ export class ProxyController extends Controller {
 
 				break;
 			case "error":
-				this.emitErrorEvent("Error inside ProxyWorker", message.error);
+				logger.error(
+					"Error proxying request to the local Worker:",
+					message.error.message
+				);
 
 				break;
 			case "debug-log":