Function check

test/utils.ts:239–241

(latex: string, variants?: Array<ExprVariant>)

  return checkJson(engine.parse(latex, { form: 'raw' }), variants);
}

export function latex(expr: Expression | undefined | null): string {
  if (expr === undefined) return 'UNDEFINED';
  if (expr === null) return 'NULL';

  errors = [];