[cli][dev] handle no response from edge functions (#8095)

When an edge function has no response during `vc dev`, we were seeing an unhelpful error message:

> The event listener did not respond.

Now, we'll see a much more specific error message:

> Unhandled rejection: Edge Function "api/edge-no-response.ts" did not return a response.
> Error! Failed to complete request to /api/edge-no-response: Error: socket hang up

packages/cli/test/dev/integration-4.test.ts

@@ -442,6 +442,17 @@ test(
   })
 );
 
+test(
+  '[vercel dev] Middleware that has no response',
+  testFixtureStdio('middleware-no-response', async (testPath: any) => {
+    await testPath(
+      500,
+      '/api/hello',
+      'A server error has occurred\n\nEDGE_FUNCTION_INVOCATION_FAILED'
+    );
+  })
+);
+
 test(
   '[vercel dev] Middleware that does basic rewrite',
   testFixtureStdio('middleware-rewrite', async (testPath: any) => {