Handle initialProps as optional in renderApplication

Summary:
Pass a default empty object to `AppContainer` if no `initialProps` were passed to `renderApplication`.

This prevents issues on Android, where we do not pass a default empty `initialProps` from native, as we do on iOS.

Changelog: [General] [Fixed] - Handle nullish `initialProps` correctly in `renderApplication`

Reviewed By: motiz88

Differential Revision: D21448692

fbshipit-source-id: 9630bdc2414532999abf3bf9da25047f0482fcab

Libraries/ReactNative/renderApplication.js

@@ -41,7 +41,7 @@ function renderApplication<Props: Object>(
         fabric={fabric}
         showArchitectureIndicator={showArchitectureIndicator}
         WrapperComponent={WrapperComponent}
-        initialProps={initialProps}
+        initialProps={initialProps ?? Object.freeze({})}
         internal_excludeLogBox={isLogBox}>
         <RootComponent {...initialProps} rootTag={rootTag} />
       </AppContainer>