STEPS TO REPRODUCE
1. start drawing a line with the polyline tool, in a paint layer that's within a group
2. without finishing the line, use a shortcut like page up to switch to the group itself
3. click after switching to the group and while in it, wait a few seconds, krita crashes.

OBSERVED RESULT
A crash.

EXPECTED RESULT
I stumbled onto this by accident, but by judging by its behaviour when you shortcut to another layer, I'd expect the line to complete itself as usual, altough since you can't draw in a group container krita has no idea what to do.

SOFTWARE/OS VERSIONS
Windows: 10

ADDITIONAL INFORMATION
Info from the bug window:

Krita

 Version: 4.4.2
 Languages: en_US, en, en_US, en, en_US, en, en_US, en, en_US, en, en_US, en, en_US, en, en_US, en, pt_BR, pt, en_US, en
 Hidpi: true

Qt

  Version (compiled): 5.12.9
  Version (loaded): 5.12.9

OS Information

  Build ABI: x86_64-little_endian-llp64
  Build CPU: x86_64
  CPU: x86_64
  Kernel Type: winnt
  Kernel Version: 10.0.18363
  Pretty Productname: Windows 10 (10.0)
  Product Type: windows
  Product Version: 10

OpenGL Info
 
  Vendor:  "Google Inc." 
  Renderer:  "ANGLE (Intel(R) HD Graphics Family Direct3D11 vs_5_0 ps_5_0)" 
  Version:  "OpenGL ES 3.0 (ANGLE 2.1.0.57ea533f79a7)" 
  Shading language:  "OpenGL ES GLSL ES 3.00 (ANGLE 2.1.0.57ea533f79a7)" 
  Requested format:  QSurfaceFormat(version 3.0, options
Windows 6.2.9200
DrMingw 0.8.2