Description of problem:
If you try to create new form file which name already exists in the package than the business-central application freeze with dialog "Creating new form" and in server log is exception (attached)

Version-Release number of selected component (if applicable):
6.0.0 DR6

How reproducible:

Steps to Reproduce:
1. Got to process authoring (jbpm-playground, Evaluation)
2. Create new form file which name is "evaluation-taskform" (this file already exists)

Actual results:
the business-central application freeze with dialog "Creating new form" and in server log is exception.
Helps (refreshing the browser) F5.

Expected results:
Show any alert which says that file already exist. Freezing is not acceptable.

Additional info: