Double "Convert Root to Base Node(s)" makes Webots crash in Tiago++

[BenjaminDeleze]

Steps to Reproduce

1. Open Tiago++.wbt
2. Convert Root to Base Node(s) one of the TiagoGripper
3. Convert Root to Base Node(s) one of the CapScrew inside of the TiagoGripper
4. Webots crash

Additional context Bug present at least since R2022a.

[omichel]

After the first Convert Root to Base Node(s), I am getting a warning in the console:

Warning: QObject::disconnect: Unexpected nullptr parameter

[ygoumaz]

#5467 is following-up on the warning issue.