From 4667b3f125948259a2724f0d978c39e70d0a3196 Mon Sep 17 00:00:00 2001
From: Mikhail Losev <mlosev86@gmail.com>
Date: Mon, 27 Dec 2021 11:40:09 +0300
Subject: [PATCH] fix '"Cannot read property 'tests' of null" when using client
 scripts' (close #6305) (#6771)

---
 src/custom-client-scripts/client-script.ts | 2 +-
 src/errors/runtime/templates.js            | 2 +-
 src/live/test-runner.js                    | 7 ++++++-
 test/server/custom-client-scripts-test.js  | 4 +++-
 4 files changed, 11 insertions(+), 4 deletions(-)

diff --git a/src/custom-client-scripts/client-script.ts b/src/custom-client-scripts/client-script.ts
index dedbb928bb..2476c5b185 100644
--- a/src/custom-client-scripts/client-script.ts
+++ b/src/custom-client-scripts/client-script.ts
@@ -61,7 +61,7 @@ export default class ClientScript {
             this.url     = path || this.url;
         }
         catch (e) {
-            throw new GeneralError(RUNTIME_ERRORS.cannotLoadClientScriptFromPath, path);
+            throw new GeneralError(RUNTIME_ERRORS.cannotLoadClientScriptFromPath, path, e.message);
         }
     }
 
diff --git a/src/errors/runtime/templates.js b/src/errors/runtime/templates.js
index 44bb4f5a2e..9b0d4abd8c 100644
--- a/src/errors/runtime/templates.js
+++ b/src/errors/runtime/templates.js
@@ -98,7 +98,7 @@ export default {
     [RUNTIME_ERRORS.clientScriptInitializerIsNotSpecified]:            'Initialize your client script with one of the following: a JavaScript script, a JavaScript file path, or the name of a JavaScript module.',
     [RUNTIME_ERRORS.clientScriptBasePathIsNotSpecified]:               'Specify the base path for the client script file.',
     [RUNTIME_ERRORS.clientScriptInitializerMultipleContentSources]:    'Client scripts can only have one initializer: JavaScript code, a JavaScript file path, or the name of a JavaScript module.',
-    [RUNTIME_ERRORS.cannotLoadClientScriptFromPath]:                   'Cannot load a client script from {path}.',
+    [RUNTIME_ERRORS.cannotLoadClientScriptFromPath]:                   'Cannot load a client script from {path}.\n{errorMessage}',
     [RUNTIME_ERRORS.clientScriptModuleEntryPointPathCalculationError]: 'A client script tried to load a JavaScript module that TestCafe cannot locate:\n\n{errorMessage}.',
     [RUNTIME_ERRORS.methodIsNotAvailableForAnIPCHost]:                 'This method cannot be called on a service host.',
     [RUNTIME_ERRORS.tooLargeIPCPayload]:                               'The specified payload is too large to form an IPC packet.',
diff --git a/src/live/test-runner.js b/src/live/test-runner.js
index 64cd716da4..2f95f3ceaa 100644
--- a/src/live/test-runner.js
+++ b/src/live/test-runner.js
@@ -146,7 +146,7 @@ class LiveModeRunner extends Runner {
     }
 
     async _finishPreviousTestRuns () {
-        if (!this.configurationCache.tests) return;
+        if (!this.configurationCache?.tests) return;
 
         this.testRunController.run();
     }
@@ -156,6 +156,11 @@ class LiveModeRunner extends Runner {
             if (this.bootstrappingError)
                 return Promise.reject(this.bootstrappingError);
 
+            else if (!this.configurationCache) {
+                // NOTE: Such errors handled in process.on('unhandledRejection') handler.
+                return Promise.reject(null);
+            }
+
             return Promise.resolve();
         }
 
diff --git a/test/server/custom-client-scripts-test.js b/test/server/custom-client-scripts-test.js
index ab4914d4da..695eb45ea1 100644
--- a/test/server/custom-client-scripts-test.js
+++ b/test/server/custom-client-scripts-test.js
@@ -187,7 +187,9 @@ describe('Client scripts', () => {
                 expect.fail('Should throw the error');
             })
             .catch(e => {
-                expect(e.message).eql('Cannot load a client script from /non-existing-file.');
+                expect(e.message).contains(
+                    'Cannot load a client script from /non-existing-file.\n' +
+                    'ENOENT: no such file or directory, open');
             });
     });