https://github.com/zeux/meshoptimizer/commit/4a287848fd664ae1c3fc8e5e008560534ceeb526
https://github.com/zeux/meshoptimizer/commit/ea4558d1c0f217f1d67ed7fe0b07896ece88ae18
https://github.com/zeux/meshoptimizer/commit/8a7d69caa68f778cb559f1879b6beb7987c8c6b7
Normals being optimized has better quality now. Test simplify once and then use a slightly less tolerant error for the target error.