"__ON_BEGIN__" not responding

[Faering666]

Describe the bug
I used the ON_BEGIN function to initialize some variables in my project declaration. ON_BEGIN never triggered.
I have tried to move it into a template declaration, however it still didn't trigger.

To Reproduce
Steps to reproduce the behavior:

1. Go to 'Create a system and use the ON_BEGIN'
2. Click on 'step through the system or use the verification tool'
3. See error 'No error will occur, since there is nothing that occurs'

Expected behavior
I expect the ON_BEGIN function to active "on begin", either of a system or a template

Version(s) of UPPAAL tested
I used UPPAAL 5.0.0

Screenshots
If applicable, add screenshots to help explain your problem.

Desktop (please complete the following information):

• Version [see Help About menu, or verifyta --version e.g. 4.1.25]
• OS, Java version: [e.g. Windows 10 64bit, Java 11]

Additional context
Add any other context about the problem here.