Improve test coverage

[franciszekjob]

Describe your changes

Linked issues

Closes #427

Breaking changes

• [ ] This issue contains breaking changes

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 72.00000% with 7 lines in your changes are missing coverage. Please review.

Project coverage is 70.94%. Comparing base (d28b008) to head (583bcd9). Report is 12 commits behind head on main.

Files	Patch %	Lines
...lin/com/swmansion/starknet/data/types/Contracts.kt	53.84%	3 Missing and 3 partials :warning:
.../kotlin/com/swmansion/starknet/data/types/Block.kt	66.66%	0 Missing and 1 partial :warning:

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #480      +/-   ##
==========================================
- Coverage   71.12%   70.94%   -0.18%     
==========================================
  Files          75       88      +13     
  Lines        3338     3390      +52     
  Branches      367      375       +8     
==========================================
+ Hits         2374     2405      +31     
- Misses        798      817      +19     
- Partials      166      168       +2     

:umbrella: View full report in Codecov by Sentry.
:loudspeaker: Have feedback on the report? Share it here.