bug#30787: 26.0.91; Crash in minibuffer prompt

[Juri Linkov <juri@linkov.net>]

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Please write in English if possible, as the Emacs maintainers
usually do not have translators for other languages.

Please describe exactly what actions triggered the bug, and
the precise symptoms of the bug.  If you can, give a recipe
starting from 'emacs -Q':

1. Eval:

(custom-set-variables
 '(enable-recursive-minibuffers t)
 '(minibuffer-depth-indicate-mode t)
 '(visual-order-cursor-movement t))

2. Type:

M-x M-x <left> <left> <left> <left> <left>

If Emacs crashed, and you have the Emacs process in the gdb debugger,
please include the output from the following gdb commands:
    'bt full' and 'xbacktrace'.

(gdb) xbacktrace
"move-point-visually" (0xffffb4d0)
"left-char" (0xffffb730)
"funcall-interactively" (0xffffb728)
"call-interactively" (0xffffb930)
"command-execute" (0xffffbb38)
"read-from-minibuffer" (0xffffbf90)
"completing-read-default" (0xffffc158)
"completing-read" (0xffffc2b0)
"read-extended-command" (0xffffc488)
"byte-code" (0xffffc5d0)
"call-interactively" (0xffffc820)
"command-execute" (0xffffca28)
"read-from-minibuffer" (0xffffce80)
"completing-read-default" (0xffffd048)
"completing-read" (0xffffd1a0)
"read-extended-command" (0xffffd378)
"byte-code" (0xffffd4c0)
"call-interactively" (0xffffd710)
"command-execute" (0xffffd918)

In GNU Emacs 26.0.91 (build 2, x86_64-pc-linux-gnu, GTK+ Version 3.10.8)