Note: I'm using ohmyzsh to provide autocomplete and I can't reproduce it
without ohmyzsh, but since ohmyzsh is written entirely in shell, this
should be an issue in zsh itself.

When I trigger autocomplete in one position, zsh crashes, yielding one
of the following messages, seemingly at random:

(none, zsh crashes silently)         x12
double free or corruption (out)     x5

Zsh crashed each time I tried it.

zsh 5.8 (x86_64-pc-linux-gnu)
ohmyzsh, commit 6152ac30bede172ba0422a8610dc796948ae1546

Minimal setup:
$ alias a='""'
           ^

Place cursor so it stands on the first " character and press Tab to
trigger autocomplete. Zsh crashes.

I have almost default ohmyzsh installation, the only thing I changed is
theme (to `mrtazz`) and `git` plugin, none of which should affect this.
Zsh config itself (after being modified by ohmyzsh) is unchanged, if one
doesn't count `PATH` exports. Thus I don't see the need to attach my
full config. If anyone has troubles reproducing this, let me know. But
it should be enough to have ohmyzsh installed.

-- 
Petr Šťastný
FIT ČVUT

soptik.tech