From 1eb6a85d3993fb5e40a6f3fe0716286b40c609c6 Mon Sep 17 00:00:00 2001
From: chimurai <655241+chimurai@users.noreply.github.com>
Date: Tue, 6 Apr 2021 21:14:39 +0200
Subject: [PATCH] fix(error handler): re-throw http-proxy missing target error

---
 src/handlers.ts            | 5 +++++
 test/unit/handlers.spec.ts | 7 +++++++
 2 files changed, 12 insertions(+)

diff --git a/src/handlers.ts b/src/handlers.ts
index 7e2b0e3f..e44e5dc7 100644
--- a/src/handlers.ts
+++ b/src/handlers.ts
@@ -54,6 +54,11 @@ export function getHandlers(options: Options) {
 }
 
 function defaultErrorHandler(err, req: express.Request, res: express.Response) {
+  // Re-throw error. Not recoverable since req & res are empty.
+  if (!req && !res) {
+    throw err; // "Error: Must provide a proper URL as target"
+  }
+
   const host = req.headers && req.headers.host;
   const code = err.code;
 
diff --git a/test/unit/handlers.spec.ts b/test/unit/handlers.spec.ts
index 792b7333..55789270 100644
--- a/test/unit/handlers.spec.ts
+++ b/test/unit/handlers.spec.ts
@@ -133,4 +133,11 @@ describe('default proxy error handler', () => {
     proxyError(mockError, mockReq, mockRes, proxyOptions);
     expect(errorMessage).toBe('Error occured while trying to proxy: localhost:3000/api');
   });
+
+  it('should re-throw error from http-proxy when target is missing', () => {
+    mockRes.headersSent = true;
+    const error = new Error('Must provide a proper URL as target');
+    const fn = () => proxyError(error, undefined, undefined, proxyOptions);
+    expect(fn).toThrowError(error);
+  });
 });