fix: return always the same error contract from simplifyTest (#3168)

Co-authored-by: André Mota <andre.mota@glintt.com>

lib/command/workers/runTests.js

@@ -73,6 +73,27 @@ function filterTests() {
 }
 
 function initializeListeners() {
+  function simplifyError(error) {
+    if (error) {
+      const {
+        stack,
+        uncaught,
+        message,
+        actual,
+        expected,
+      } = error;
+
+      return {
+        stack,
+        uncaught,
+        message,
+        actual,
+        expected,
+      };
+    }
+
+    return null;
+  }
   function simplifyTest(test, err = null) {
     test = { ...test };
 
@@ -82,13 +103,10 @@ function initializeListeners() {
     }
 
     if (test.err) {
-      err = {
-        stack: test.err.stack,
-        uncaught: test.err.uncaught,
-        message: test.err.message,
-        actual: test.err.actual,
-        expected: test.err.expected,
-      };
+      err = simplifyError(test.err);
+      test.status = 'failed';
+    } else if (err) {
+      err = simplifyError(err);
       test.status = 'failed';
     }
     const parent = {};