Re: 23.0.50; Crash in ediff-regions-linewise

[Richard Stallman]

    The first sign of invalid data that I can find shows up at
    buffer.c:603:

      XSETBUFFER (buf, b);

You have made substantial progress, but this is not the end of the
debugging.

Next step: figure out whether b is invalid, and if so, where it came
from, and why that is invalid, etc...