C image bindings: Add null pointer checks

[SahilSonar-04]

Added Null Pointer checks for image c bindings

Fixes Issue : #3393

Checklist for finalizing the PR

• I have performed a self-review of my code
• I have added tests for new features and bugfixes
• I have added documentation for new features
• If it is a modifying the libf3d API, I have updated bindings
• If it is a modifying the .github/workflows/versions.json, I have updated docker_timestamp

AI Disclosure

• I have not used AI to generate any of the content of this pull request
• I have used AI to generate code in this pull request:
• I have carefully read and understood the AI policy.
• I have carefully reviewed and completely understood every generated line.
• I disclose below which parts of the code were generated and with which AI model:

[mwestphal]

Please properly disclose AI usage. Check only the correct checkbox. In the top part too.

[mwestphal]

Improper AI disclosure.

[mwestphal]

Thanks for fixing it @SahilSonar-04 !

[mwestphal]

Looks fine however I think that:

• (almost) each of these should print an error
• all the docs should be updated

[SahilSonar-04]

Looks fine however I think that:

• (almost) each of these should print an error
• all the docs should be updated

Wouldn't these cause inconsistencies ?
As other c binding files rn follow the same pattern

[mwestphal]

As other c binding files rn follow the same pattern

Maybe I'm wrong about printing an error, thats why I asked for @Meakk input.

However the doc defintely should mention this behavior, if it does not, it is missing.

[SahilSonar-04]

Done with the documentation , Do let me know if any changes required , also about the error messages

[mwestphal]

changes needed

[Meakk]

\ci fast

[mwestphal]

other small changes, also CI is red

[SahilSonar-04]

\ci extended

[SahilSonar-04]

\ci full

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 97.08%. Comparing base (e236322) to head (ce47b01).
⚠️ Report is 3 commits behind head on master.

Additional details and impacted files

@@           Coverage Diff           @@
##           master    #3394   +/-   ##
=======================================
  Coverage   97.08%   97.08%           
=======================================
  Files         216      216           
  Lines       18750    18771   +21     
=======================================
+ Hits        18203    18224   +21     
  Misses        547      547           

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