/usr/share/imapfilter/regex.lua:10: bad argument #1 to 'compile' (string expected, got nil)

[Seth Forshee]

Started getting this error after upgrading from 1:2.6.16-1 to 1:2.7.2-1. Gives the following stacktrace:

$ /usr/bin/imapfilter -c ~/.imapfilter/mail.lua
imapfilter: /usr/share/imapfilter/regex.lua:10: bad argument #1 to 'compile' (string expected, got nil)
stack traceback:
        [C]: in ?
        [C]: in function 'compile'
        /usr/share/imapfilter/regex.lua:10: in function '__index'
        /usr/share/imapfilter/regex.lua:21: in function 'regex_search'
        /usr/share/imapfilter/mailbox.lua:986: in function 'match_field'
        /usr/share/imapfilter/set.lua:629: in function 'match_field'
        /home/sforshee/.imapfilter/mail.lua:15: in main chunk

ProblemType: Bug
DistroRelease: Ubuntu 21.04
Package: imapfilter 1:2.7.2-1
ProcVersionSignature: Ubuntu 5.8.0-25.26-generic 5.8.14
Uname: Linux 5.8.0-25-generic x86_64
NonfreeKernelModules: zfs zunicode zavl icp zcommon znvpair
ApportVersion: 2.20.11-0ubuntu51
Architecture: amd64
CasperMD5CheckResult: skip
CurrentDesktop: GNOME
Date: Tue Nov 17 14:00:44 2020
InstallationDate: Installed on 2020-02-07 (284 days ago)
InstallationMedia: Ubuntu 20.04 LTS "Focal Fossa" - Alpha amd64 (20200124)
ProcEnviron:
 TERM=screen-256color
 PATH=(custom, no user)
 XDG_RUNTIME_DIR=<set>
 LANG=en_US.UTF-8
 SHELL=/bin/bash
SourcePackage: imapfilter
UpgradeStatus: No upgrade log present (probably fresh install)

[Seth Forshee (sforshee)]

I filed a bug upstream, the issue is fixed in v2.7.4.

https://github.com/lefcha/imapfilter/issues/218

Here's the fix:

https://github.com/lefcha/imapfilter/commit/987ea442fa0aa3dc5f5d59ec89c9a3d818cd48d3