Fix null pointer dereference in Composable::available_image_bounds

[La1itchauhan]

Fixes #2045

Composable::available_image_bounds(ErrorStatus* error_status) was writing directly to *error_status without checking if the pointer was null. Because error_status defaults to nullptr, calling available_image_bounds() on Composable or derived classes that do not override it (such as Gap and Transition) caused a segmentation fault.

• Added a null check before writing ErrorStatus::NOT_IMPLEMENTED to *error_status, consistent with Composable::duration.
• Resolves the crash for all non-overriding subclasses (including Gap and Transition) inheriting the base implementation.

Reference associated tests.

• Added test_composable_available_image_bounds in tests/test_composition.cpp verifying that calls with default nullptr and explicit nullptr do not crash, and that passing an ErrorStatus pointer correctly reports NOT_IMPLEMENTED.
• Added test_available_image_bounds in tests/test_item.py to cover the Python bindings.

[linux-foundation-easycla]

The committers listed above are authorized under a signed CLA.

• ✅ login: La1itchauhan / name: La1itchauhan (2b0b748)

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 83.60%. Comparing base (dcf9ac1) to head (ee4dce5).

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #2055      +/-   ##
==========================================
+ Coverage   83.58%   83.60%   +0.02%     
==========================================
  Files         182      182              
  Lines       13570    13575       +5     
  Branches     1260     1261       +1     
==========================================
+ Hits        11342    11350       +8     
+ Misses       2055     2052       -3     
  Partials      173      173              

Flag	Coverage Δ
py-unittests	83.60% <100.00%> (+0.02%)	⬆️

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Files with missing lines	Coverage Δ
src/opentimelineio/composable.cpp	67.74% <100.00%> (+11.07%)	⬆️
tests/test_item.py	98.69% <100.00%> (+0.03%)	⬆️

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[jminor]

Hi @La1itchauhan - thanks, this PR is looking pretty good. We'll arrange for an OTIO committer to review it.

Out of curiosity, how did you come across this issue, and what lead you to contribute to OTIO?

[La1itchauhan]

Hi @jminor,
First, my sincere apologies for the delayed response I was dealing with some health complications over the past couple of weeks and had to step away from the keyboard . Thank you so much for taking the time to review and approve the PR
To answer your question , I came across this issue through ASWF Dev Days 2026. I've been actively exploring and contributing across the Academy Software Foundation ecosystem previously working on rawtoaces and MaterialX.
As an engineering student with a strong interest in C++ systems and media pipeline infrastructure, OpenTimelineIO immediately stood out to me. Editorial interchange is such an essential standard for modern VFX and animation workflows