Backport of UI: Handle error from ResponseWithStatusCode (#23116)

Co-authored-by: Chelsea Shaw <82459713+hashishaw@users.noreply.github.com>

ui/app/adapters/application.js

@@ -119,10 +119,18 @@ export default RESTAdapter.extend({
 
   handleResponse(status, headers, payload, requestData) {
     const returnVal = this._super(...arguments);
-    // ember data errors don't have the status code, so we add it here
     if (returnVal instanceof AdapterError) {
+      // ember data errors don't have the status code, so we add it here
       set(returnVal, 'httpStatus', status);
       set(returnVal, 'path', requestData.url);
+      // Most of the time when the Vault API returns an error, the payload looks like:
+      // { errors: ['some error message']}
+      // But sometimes (eg RespondWithStatusCode) it looks like this:
+      // { data: { error: 'some error message' } }
+      if (payload?.data?.error && !payload.errors) {
+        // Normalize the errors from RespondWithStatusCode
+        set(returnVal, 'errors', [payload.data.error]);
+      }
     }
     return returnVal;
   },