onMapReady property
OnMapReady is called after the map runs it's initState. At that point the map has assigned its state to the controller Only use this if your map isn't built immediately (like inside FutureBuilder) and you need to access the controller as soon as the map is built. Otherwise you can use WidgetsBinding.instance.addPostFrameCallback In initState to controll the map before the next frame.
Implementation
final VoidCallback? onMapReady;