fix(app.tsx): add safe check for readyPromise (#2489)

* fix(app.tsx): add safe check for readyPromise

* make type-safe

Co-authored-by: dwelle <luzar.david@gmail.com>

src/global.d.ts

@@ -43,6 +43,9 @@ type ResolutionType<T extends (...args: any) => any> = T extends (
 // https://github.com/krzkaczor/ts-essentials
 type MarkOptional<T, K extends keyof T> = Omit<T, K> & Partial<Pick<T, K>>;
 
+type MarkRequired<T, RK extends keyof T> = Exclude<T, RK> &
+  Required<Pick<T, RK>>;
+
 // PNG encoding/decoding
 // -----------------------------------------------------------------------------
 type TEXtChunk = { name: "tEXt"; data: Uint8Array };