Re: signalling errors in redisplay

[Richard Stallman]

    Because the other redisplay initiated by Fsignal will again try to
    display the same portion which caused the error, which will again call
    Fsignal, etc., ad nauseum.

Fsignal itself doesn't do this, but it usually sends control back to
the main loop.  And the next thing that will typically do is redisplay.
So when things can cause errors in redisplay, there is always
a danger of an infinite loop of errors.

One solution is that the code that signals the error first could do
something to change the data structures so the error won't repeat.
This isn't a universal solution, but it may be applicable in some
cases.

I don't know if we can expect to find any universal solution.