Templates throw an error when values are substitued which contain invalid regular expression sequences.

This is because the replacement string passed to String.replaceAll is parsed for certain significant strings such as regular expression group references ($n) and escaped literals (\x) and we do not escape these sequences.

Symptoms:

StringIndexOutOfBoundsException - when replacement text ends in a backslash
IllegalArgumentException: Illegal group reference - when replacement text contains a dollar sign followed by a number