Re: font-lock and shell scripts: Raises redisplay errors in highlight pattern:

[Richard Stallman]

    1) Might be marginally benefitial even for the mainstream emacs user
    to not have these errors raised and handled --
    --- what variables in my sh-mode/font-lock environment should I
    look at to chase down and fix the cause of the error in the first
    place? (Note that I'm running with font-lock turned on at the
    highest level).

If there is no good reason for this to signal an error, it would be
cleaner to eliminate it.  But first one has to track down what causes
the error.  One way to do that is using GDB with a breakpoint at
Fsignal.  Setting debug-on-signal might enable you to find the cause
using the Lisp debugger.

    When (error ...) is called:

    Before-Advice:

    A)      Check if there is a handler waiting to catch the error.
    B)      If yes, do nothing;
    C) Else give the user auditory feedback.

Unhandled errors do make a beep, which is auditory feedback.  So what
is the change that you propose?