Fix cases when png reader ended up in an infinite loop. #774

[Processor228]

Additionally, throw exceptions directly, instead of handling errors by longjumps.

Longjumps lead to segfaults under compiler optimizations.

Besides, setjmp setups always ended up throwing
exceptions, so why not throwing them right away instead?

Description

A fix for issue #774, case when png reader ends up in infinite loop.

References

issue #774

Tasklist

• Add test case(s)
• Ensure all CI builds pass
• Review and approve

[mloskot]

Although I'm not libpng expert, I'm inclined to approve it. The setjmp always been itching me too :) Thanks!
If not objections arrive in couple of days, this will be merged.

[codecov]

Codecov Report

❌ Patch coverage is 25.00000% with 6 lines in your changes missing coverage. Please review.
✅ Project coverage is 81.97%. Comparing base (06c421a) to head (6281653).
⚠️ Report is 28 commits behind head on develop.

Additional details and impacted files

@@             Coverage Diff             @@
##           develop     #780      +/-   ##
===========================================
- Coverage    82.34%   81.97%   -0.38%     
===========================================
  Files          117      117              
  Lines         5726     5353     -373     
===========================================
- Hits          4715     4388     -327     
+ Misses        1011      965      -46     

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[mloskot]

Thank you @Processor228 !