[#373] Switch to mocks for Functional ErrorHandlerTest (#390)

Author: shadcn

tests/src/Functional/ErrorHandlerTest.php

@@ -29,6 +29,11 @@
  */
 class ErrorHandlerTest extends ApigeeEdgeFunctionalTestBase {
 
+  /**
+   * {@inheritdoc}
+   */
+  protected static $mock_api_client_ready = TRUE;
+
   /**
    * User prefix.
    *
@@ -78,8 +83,6 @@ public function testErrorPages() {
     ];
 
     $routes = [
-      'apigee_edge_test.entity_storage_exception',
-      'apigee_edge_test.api_exception',
       'entity.developer_app.collection_by_developer',
       'entity.developer_app.add_form_for_developer',
       'entity.developer_app.canonical_by_developer',