Error when dropping a predicate

[danielmai]

When I try to drop a predicate using the red Drop button for a predicate in the Schema tab, Ratel loses connection with Dgraph Alpha and shows the error: "Could not drop predicate: Could not connect to the server: Failed to fetch".

In the dev tool console, I see this error:

Failed to load http://localhost:8180/[object%20Object]: No 'Access-Control-Allow-Origin' header is present on the requested resource. Origin 'http://localhost:8000' is therefore not allowed access. If an opaque response serves your needs, set the request's mode to 'no-cors' to fetch the resource with CORS disabled.

This happens in both dev and latest.