Description of problem:
If I want to open process which is invalid or which contains unsupported element by Designer then exception in server.log is shown and loading of Designer freezes.

(this is realistic scenario because git repository has no protection. An user can write own BPMN definition and add it into repository)

Version-Release number of selected component (if applicable):
6.0.0 BPMS ER2

How reproducible:

Steps to Reproduce:
1. Add invalid BPMN2 definition into git repository.
2. Go to business central
3. Clone this repository
4. Open process

Actual results:
---------------
Loading of designer freezes, server.log shows some exception like:

• Could not find BPMNDI information:
• Event definition not supported: org.eclipse.bpmn2.impl.CancelEventDefinitionImpl@5d115595

Common user does not know what happend. The user must have access to server.log if he want to know what happend.

Expected results:
-----------------
Stop loading of designer, shows some error page or alerts which describe actual problem.

My idea is that instead of Designer, a simple text editor is opened. This editor contains:

• actual problem (highlighted line or simply write a message of exception into alert)
• operation for writing, saving, deleting
• source code of BPMN2 definition.

Now only way, how to delete or correct an invalid BPMN2 process, is an access to git repo.

Additional info: