Fix interface out of bounds error on MSYS2

[rory-cd]

Description

Problem

Interfaces have a bug which can cause out-of-bounds errors in MSYS2. When running the UI test in MSYS2 via sktest.exe, the following error is received:

C:/msys64/mingw64/include/c++/15.2.0/bits/stl_vector.h:1263: constexpr std::vector<_Tp, _Alloc>::ref
erence std::vector<_Tp, _Alloc>::operator[](size_type) [with _Tp = int; _Alloc = std::allocator<int>
; reference = int&; size_type = long long unsigned int]: Assertion '__n < this->size()' failed.

Cause

The error can be traced back to interface.cpp, line 308 in the _update_row_layout function, which has:

sk_interface_set_layout(container_stack.back().layout_widths.size(), &container_stack.back().layout_widths[0], container_stack.back().layout_height);

This line attempts to access the layout_widths vector's first element (container_stack.back().layout_widths[0]), but many callers of _update_row_layout clear layout_widths beforehand, meaning the vector is empty and the out-of-bounds error occurs.

Fix

A simple guard has been added to _update_row_layout, to check if layout_widths is empty before proceeding.

Type of change

• Bug fix (non-breaking change which fixes an issue)

How Has This Been Tested?

Tested primarily using the UI test in sktest.exe in MSYS2 and WSL. Interface displays as expected, with no errors received:

Testing Checklist

• Tested with sktest
• Tested with skunit_tests

Note for Testers

There have been some reported issues running sktest (at all) on MSYS2. Specifically, the animation test was found to loop indefinitely, and some users found the test runner was freezing even before tests were launched. This has been addressed in #132.

Checklist

• My code follows the style guidelines of this project
• I have performed a self-review of my own code
• I have commented my code in hard-to-understand areas
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• I have requested a review from ... on the Pull Request