mark unused vars as errors

Reviewed By: lblasa

Differential Revision: D50500690

fbshipit-source-id: 6f739fe25c232ecfe842337af4399681e85f6a13

desktop/flipper-ui-browser/src/global.tsx

@@ -7,6 +7,8 @@
  * @format
  */
 
+// otherwise there is an error with `declare global`
+// eslint-disable-next-line @typescript-eslint/no-unused-vars
 import type {RenderHost} from 'flipper-ui-core';
 
 declare global {