When the error appears:

When staring mincraft while my android device is connected to a wifi but there is no internet.

Error:

After the loading screen the background appears but the main menu not. No action is possible at all.

Reproduction steps: 

1. Close minecraft on device and remove also from background apps.
2. Take a wifi router, make sure no WAN is connected.
3. Connect android device to this wifi
4. Start minecraft
5. Error is visible

Reproduced on Samsung Galaxy S7 and A50

I use this way to allow my kids to play together on local network, on places where no internet is availble, or I do not want them to connect.