Minted does not have a language option but it is possible to enter
this option in the LyX interface for compatibility with the listings
package, and also for letting to enter a language not present in the
gui. So, this option is only used for properly specifying a language
in a listing, unless it is entered in the document settings dialog.
This case was not foreseen and thus the option was being passed to
the package as is, causing havoc. With this commit the option is
still available but is used to set a default language for a new
listing in place of the default "tex" language used so far.