Fixed a bunch of prettier errors after upgrading

Summary: prettier upgrade uncovered more errors

Reviewed By: passy

Differential Revision: D18474908

fbshipit-source-id: b1553000fb3386f2bbd9defdd3332618e4b9c867

src/plugins/navigation/index.tsx

@@ -53,7 +53,7 @@ export default class extends FlipperPlugin<State, any, PersistedState> {
 
   state = {
     shouldShowSaveBookmarkDialog: false,
-    saveBookmarkURI: null as (string | null),
+    saveBookmarkURI: null as string | null,
     shouldShowURIErrorDialog: false,
     requiredParameters: [],
   };