Expect GraphQL errors to be an Array

app/assets/javascripts/snippets/components/snippet_header.vue

@@ -138,7 +138,7 @@ export default {
           variables: { id: this.snippet.id },
         })
         .then(({ data }) => {
-          if (data?.destroySnippet?.errors) {
+          if (data?.destroySnippet?.errors.length) {
             throw new Error(data?.destroySnippet?.errors[0]);
           }
           this.isDeleting = false;

spec/frontend/snippets/components/snippet_header_spec.js

@@ -32,7 +32,9 @@ describe('Snippet header component', () => {
   const errorMsg = 'Foo bar';
   const err = { message: errorMsg };
 
-  const resolveMutate = jest.fn(() => Promise.resolve({ data: {} }));
+  const resolveMutate = jest.fn(() =>
+    Promise.resolve({ data: { destroySnippet: { errors: [] } } }),
+  );
   const rejectMutation = jest.fn(() => Promise.reject(err));
 
   const mutationTypes = {