fix: Error occuring when adding a data task after creating a subform

[ErlingHauan]

Description

This fixes an error that occurs when adding a new task in the process editor, when layout-sets.json contains a layout set without the tasks property. The solution was to add null checks.

Since we now allow layout sets to not contain tasks (which is the case for subform layout sets), we have to check if the tasks property exists before trying to access it.

Note: the backend build warnings in the PR comments should likely be solved en masse, see this issue: #13738

Related Issue(s)

• An error occurs when adding a data task after creating a subform #13690

Verification

• Your code builds clean without any errors or warnings
• Manual testing done (required)
• Relevant automated test added (if you find this hard, leave it and we'll help out)

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 94.54%. Comparing base (a591d37) to head (00700e9).
Report is 1 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main   #13736   +/-   ##
=======================================
  Coverage   94.54%   94.54%           
=======================================
  Files        1621     1621           
  Lines       21677    21678    +1     
  Branches     2549     2549           
=======================================
+ Hits        20495    20496    +1     
  Misses        939      939           
  Partials      243      243           

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

[JamalAlabdullah]

I tested it and I wonder about the erro-toast that showing when adding a task?
https://github.com/user-attachments/assets/c9421389-1a4b-4618-9cb3-a845c4a1e697

[JamalAlabdullah]

Bra jobba😊; I tested it now and works fine.

[ErlingHauan]

Added label skip-manual-testing to get an automatic approval, since this is a very small PR that @JamalAlabdullah has both code reviewed and tested.