Fix invalid "array to string conversion" in ScriptHandler exception m…

…essage (see #2184)

Description
-----------

| Q                | A
| -----------------| ---
| Fixed issues     | Fixes contao/manager-bundle#88
| Docs PR or issue | -

There is indeed a missing implode at this place.

Commits
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83c3889 add a missing array->string conversion in the exception message

manager-bundle/src/Composer/ScriptHandler.php

@@ -92,7 +92,7 @@ static function (string $type, string $buffer) use ($event): void {
         );
 
         if (!$process->isSuccessful()) {
-            throw new \RuntimeException(sprintf('An error occurred while executing the "%s" command: %s', $cmd, $process->getErrorOutput()));
+            throw new \RuntimeException(sprintf('An error occurred while executing the "%s" command: %s', implode(' ', $cmd), $process->getErrorOutput()));
         }
     }