Issue 6822 - Report browser test errors

test_runner.js

 /*
  * This file is part of Adblock Plus <https://adblockplus.org/>,
  * Copyright (C) 2006-present eyeo GmbH
  *
  * Adblock Plus is free software: you can redistribute it and/or modify
  * it under the terms of the GNU General Public License version 3 as
  * published by the Free Software Foundation.
  *
  * Adblock Plus is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
@@ skipping 135 matching lines @@
     }
   }).then(bundle =>
     Promise.all(
       processes.map(currentProcess =>
         runnerDefinitions[currentProcess](
           bundle, bundleFilename,
           browserFiles.map(
             file => path.relative(path.join(__dirname, "test", "browser"),
                                   file).replace(/\.js$/, "")
           )
+        ).catch(error => Promise.reject(
+          `Unit test "${currentProcess}" failed: ${error}`)
         )
       )
     )
   );
 }
 
 if (process.argv.length > 2)
   addTestPaths(process.argv.slice(2), true);
 else
 {
   addTestPaths(
     [path.join(__dirname, "test"), path.join(__dirname, "test", "browser")],
     true
   );
 }
 
-Promise.resolve(runBrowserTests(runnerProcesses)).catch(error =>
-{
-  console.error("Failed running browser tests");
-  console.error(error);
-}).then(() =>
+Promise.resolve(runBrowserTests(runnerProcesses)).then(() =>
 {
   if (unitFiles.length)
     nodeunit.reporters.default.run(unitFiles);
+}).catch(error =>
+{
+  if (!error)
+    console.error("Failed running browser tests");
+  else
+    console.error(error);
+  process.exit(1);
 });