[backend] Validate contracts undefined, null or empty (#1121)

[savacano28]

Proposed changes

• Validate when contracts maps is null, empty or undefined

Related issues

• the select inject panel can make a scenario page crash #1121

Checklist

• I consider the submitted work as finished
• I tested the code for its functionality
• I wrote test cases for the relevant uses case
• I added/update the relevant documentation (either on github or on notion)
• Where necessary I refactored code to improve the overall quality

Further comments

If this is a relatively large or complex change, kick off the discussion by explaining why you chose the solution you did and what alternatives you considered, etc...

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 26.17%. Comparing base (6f6f545) to head (0a15268).

❗ Current head 0a15268 differs from pull request most recent head 824abe3

Please upload reports for the commit 824abe3 to get more accurate results.

Additional details and impacted files

@@             Coverage Diff              @@
##             master    #1156      +/-   ##
============================================
+ Coverage     25.90%   26.17%   +0.27%     
- Complexity     1062     1066       +4     
============================================
  Files           481      481              
  Lines         11602    11602              
  Branches        609      609              
============================================
+ Hits           3005     3037      +32     
+ Misses         8512     8480      -32     
  Partials         85       85              

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