ParserErrorCode:
    | "unknown-command"
    | "invalid-command"
    | "unbalanced-braces"
    | "unknown-environment"
    | "unbalanced-environment"
    | "unbalanced-mode-shift"
    | "missing-argument"
    | "too-many-infix-commands"
    | "unexpected-command-in-string"
    | "missing-unit"
    | "unexpected-delimiter"
    | "unexpected-token"
    | "unexpected-end-of-string"
    | "improper-alphabetic-constant"

Error codes returned by the mf.errors property.

unknown-command There is no definition available for this LaTeX command, e.g. \zin
unknown-environment There is no definition available for this environment, e.g. \begin{foo}
invalid-command This command is not valid in the current context (e.g. text command in math mode)
unbalanced-braces There are too many or too few { or }
unbalanced-environment An environment was open but never closed (\begin{array}) or the \end command does not match the \begin command (\begin{array*}\end{array})
unbalanced-mode-shift A $, $$, \( or \[ was not balanced
missing-argument A required argument is missing, e.g. \frac{2}
too-many-infix-commands A group can include only one infix command (i.e. \choose, \atop). In general it's best to avoid infix commands.
unexpected-command-in-string A command expected a string argument, but there was a command instead
missing-unit An argument requiring a dimension was missing an unit.
unexpected-delimiter An invalid symbol or command was used as a delimiter.
unexpected-token An unexpected character was encountered.
unexpected-end-of-string The end of the string was reached, but some required arguments were missing.
improper-alphabetic-constant The alphabetic constant prefix ` was not followed by a letter or single character command.