diff --git a/src/FirebaseAuthenticationServiceProvider.php b/src/FirebaseAuthenticationServiceProvider.php
index 3a46fb7..bd5d148 100644
--- a/src/FirebaseAuthenticationServiceProvider.php
+++ b/src/FirebaseAuthenticationServiceProvider.php
@@ -31,9 +31,15 @@ public function boot()
     public function register()
     {
         $this->app->singleton(Verifier::class, function ($app) {
+            $project = config('firebase.project_id', env('GOOGLE_CLOUD_PROJECT'));
+
+            if (empty($project)) {
+                throw new \Exception('Missing GOOGLE_CLOUD_PROJECT env variable.');
+            }
+
             $keyStore = new HttpKeyStore(null, cache()->store());
 
-            return new Verifier(config('firebase.project_id', env('GOOGLE_CLOUD_PROJECT')), $keyStore);
+            return new Verifier($project, $keyStore);
         });
     }
 }
diff --git a/src/FirebaseGuard.php b/src/FirebaseGuard.php
index c5adc5b..91ab86a 100644
--- a/src/FirebaseGuard.php
+++ b/src/FirebaseGuard.php
@@ -35,6 +35,10 @@ public function user(Request $request)
     {
         $token = $request->bearerToken();
 
+        if (empty($token)) {
+            return;
+        }
+
         try {
             $token = $this->verifier->verifyIdToken($token);