A segmentation fault occurred while parsing an MD5 file that contains an invalid vertex index.
The issue was caused by mScene->mMaterials not being kept in sync with mScene->mNumMaterials.
As a result, the aiScene destructor could call delete on uninitialized pointers. This patch
ensures that mScene->mNumMaterials always matches the actual contents of the mScene->mMaterials
array. That way, if an exception is thrown during file import, delete is only called for
properly allocated aiMaterial objects.
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