This error as it stands is a little misleading: it's the only case where we emit an error like this when the sizes aren't equal, so it can hit when the output count is larger (so there's technically enough data, but the glTF file is still invalid per spec / per Khronos validator). In other cases where a size mismatches like this we currently emit invalid_gltf so this seems to make more sense.
The build error was unrelated to the PR (glTF-Sample-Models changed from master to main) but it was just one line to fix so I fixed it in this PR as it would need that fix to become green anyway.
This error as it stands is a little misleading: it's the only case where we emit an error like this when the sizes aren't equal, so it can hit when the output count is larger (so there's technically enough data, but the glTF file is still invalid per spec / per Khronos validator). In other cases where a size mismatches like this we currently emit invalid_gltf so this seems to make more sense.