diff --git a/src/web/_web_auth.ts b/src/web/_web_auth.ts
index 8522404b0..521abf1fa 100644
--- a/src/web/_web_auth.ts
+++ b/src/web/_web_auth.ts
@@ -17,14 +17,16 @@ export class WebAuth implements Auth {
       return;
     }
 
-    if (this.apiKey.startsWith('auth_tokens/')) {
-      throw new Error('Ephemeral tokens are only supported by the live API.');
-    }
-
     // Check if API key is empty or null
     if (!this.apiKey) {
       throw new Error('API key is missing. Please provide a valid API key.');
     }
+
+    if (this.apiKey.startsWith('auth_tokens/')) {
+      throw new Error('Ephemeral tokens are only supported by the live API.');
+    }
+
+    
     headers.append(GOOGLE_API_KEY_HEADER, this.apiKey);
   }
 }