[10.x] Fixes missing Throwable import and handle if `originalExcept…

…ionHandler` or `originalDeprecationHandler` property isn't used by alternative TestCase (#50021)

* [10.x] Fixes missing `Throwable` import.

Signed-off-by: Mior Muhammad Zaki <crynobone@gmail.com>

* wip

Signed-off-by: Mior Muhammad Zaki <crynobone@gmail.com>

* Apply fixes from StyleCI

---------

Signed-off-by: Mior Muhammad Zaki <crynobone@gmail.com>
Co-authored-by: StyleCI Bot <bot@styleci.io>

src/Illuminate/Foundation/Testing/Concerns/InteractsWithTestCaseLifecycle.php

@@ -25,6 +25,7 @@
 use Illuminate\View\Component;
 use Mockery;
 use Mockery\Exception\InvalidCountException;
+use Throwable;
 
 trait InteractsWithTestCaseLifecycle
 {
@@ -145,8 +146,13 @@ protected function tearDownTheTestEnvironment(): void
         $this->afterApplicationCreatedCallbacks = [];
         $this->beforeApplicationDestroyedCallbacks = [];
 
-        $this->originalExceptionHandler = null;
-        $this->originalDeprecationHandler = null;
+        if (property_exists($this, 'originalExceptionHandler')) {
+            $this->originalExceptionHandler = null;
+        }
+
+        if (property_exists($this, 'originalDeprecationHandler')) {
+            $this->originalDeprecationHandler = null;
+        }
 
         AboutCommand::flushState();
         Artisan::forgetBootstrappers();