Fix duplicated sign in event (#28777)

GitOrigin-RevId: 92e81160b34207a215113a2af93206ca623adb52

services/web/types/writefull/writefull-window.ts

@@ -1,4 +1,5 @@
 export interface WritefullWindow {
+  isLoaded?: boolean
   cm6?: any
   overleafUserId?: string
 }