Can't find resource for bundle java.util.PropertyResourceBundle, key badSuccessorNotice.Message

[mikucionisaau]

Describe the bug
Symbolic simulator issues "Internal Error" with message
"Can't find resource for bundle java.util.PropertyResourceBundle, key badSuccessorNotice.Message"

which is obscure and does not explain the issue.
The bug is a failure to translate the simulator error message.

To Reproduce
Steps to reproduce the behavior:

1. Create a model where an edge transition update leads to a violation of target location invariant.
2. Swich to "Symbolic Simulator"
3. Execute the disabled edge transition
4. Observe the "Internal Error" popup

Expected behavior
The error message should say that "the successor of this transition is not well defined", perhaps it can be narrowed down to "the successor of this transition violates the invariant and hence the transition is disabled".

Version(s) of UPPAAL tested

UPPAAL 5.0.0
UPPAAL 5.1.0-beta5

Desktop (please complete the following information):

Not specific to OS.