From 3f96a128a0382477e16cb84b4d565dcf69a32f47 Mon Sep 17 00:00:00 2001
From: Jerko Steiner <jerko.steiner@gmail.com>
Date: Mon, 25 Mar 2019 13:27:33 +0800
Subject: [PATCH] packages/server: Return API errors as JSON

---
 packages/server/src/middleware/ErrorApiHandler.ts | 2 +-
 packages/server/src/validator/ValidationError.ts  | 6 ++++++
 2 files changed, 7 insertions(+), 1 deletion(-)

diff --git a/packages/server/src/middleware/ErrorApiHandler.ts b/packages/server/src/middleware/ErrorApiHandler.ts
index 275e14c..dc8a14d 100644
--- a/packages/server/src/middleware/ErrorApiHandler.ts
+++ b/packages/server/src/middleware/ErrorApiHandler.ts
@@ -11,7 +11,7 @@ export class ErrorApiHandler implements IMiddleware {
       req.correlationId, err.stack)
     const statusCode = this.getStatus(err)
     res.status(statusCode)
-    if (err instanceof ValidationError) {
+    if (ValidationError.isInstanceOf(err)) {
       res.json({
         error: err.message,
         errors: err.errors,
diff --git a/packages/server/src/validator/ValidationError.ts b/packages/server/src/validator/ValidationError.ts
index d310f55..debf4be 100644
--- a/packages/server/src/validator/ValidationError.ts
+++ b/packages/server/src/validator/ValidationError.ts
@@ -15,4 +15,10 @@ export class ValidationError extends Error {
     this.name = 'ValidationError'
     Error.captureStackTrace(this)
   }
+
+  static isInstanceOf(err: any): err is ValidationError {
+    return typeof err.status === 'number'
+      && typeof err.message === 'string'
+      && Array.isArray(err.errors)
+  }
 }