Display error message in the UI,
if the check command passes,
but the mml/svg/complete endpoints returns an valid json error.
Bug: T143225
Change-Id: I50776926e42f75a2c1e30fc9afe08baae3fcdbd1
* Add support for LaTeX package mhchem.
* Add hook <ce>
* Add format <math chem>
See bug description for the details.
Bug: T98306
Change-Id: I2ab80834edc5d071618bc52f133cfb2b7ece5016