Fix the command being null in the CommandStarting event (#194)

Fixes #193

Author: stayallive

src/Sentry/Laravel/EventHandler.php

@@ -294,7 +294,9 @@ protected function queueJobProcessedHandler(JobProcessed $event)
     protected function commandStartingHandler(CommandStarting $event)
     {
         Integration::configureScope(function (Scope $scope) use ($event): void {
-            $scope->setTag('command', $event->command);
+            if ($event->command) {
+                $scope->setTag('command', $event->command);
+            }
         });
     }