Use of C-M-i (completion-at-point) in the Pascal mode results in errors.
Here is a way to reproduce the problem:
1. Start emacs by "emacs -Q".
2. Open a new file with extension "pas" (say, test.pas).
3. Type in: program test; var and then use C-M-i.
This should yields an error message like:
completion--some: Args out of range: #("var" 0 3 (fontified t face
font-lock-type-face)), 0, -14
In GNU Emacs 26.1 (build 2, x86_64-pc-linux-gnu, GTK+ Version 3.24.5)
of 2019-09-22, modified by Debian built on x86-grnet-01
Windowing system distributor 'The X.Org Foundation', version 11.0.12004000
System Description: Debian GNU/Linux 10 (buster)