fix: complete InvesteMoz validation and error corrections

app/Http/Controllers/LandAssistanceController.php

@@ -377,6 +377,9 @@ class LandAssistanceController extends Controller
             'declaredOrigin' => $countries->describe($payload['declared_origin_country_code'] ?? null), 'territoryPaths' => $paths, 'returnDossier' => $this->dossierContext($case)];
     }
 
+    /**
+     * @return array<array-key, mixed>|null
+     */
     private function dossierContext(LandAssistanceCase $case): ?array
     {
         $id = $case->payload['investor_path_case_id'] ?? null;