[PM2][ERROR] Expect "kill_timeout" to be a typeof [object Number], but now is [object String] when using -k _ option in hbbr

[JustGitting]

Describe the bug
When I start hbbr with the "-k _" to only allow clients with the public key to connect I get the following error:

$ pm2 start /opt/rustdesk-server/hbbr -k _
[PM2][WARN] Expect "kill_timeout" to be a typeof [object Number], but now is [object String]
[PM2][ERROR] Expect "kill_timeout" to be a typeof [object Number], but now is [object String]

If I run hbbr without the "-k _" option, it starts fine.

I'm not sure if this is a PM2 or rustdesk-server problem.

Describe the environment

OS: Devuan GNU/Linux 5 (daedalus) (based on Debian)
Rustdesk-server: v1.1.9, binary (rustdesk-server-linux-amd64.zip)
PM2: v5.3.1

How to Reproduce the bug

Setup following the guide at https://rustdesk.com/docs/en/self-host/rustdesk-server-oss/install/

Starting both services without the "-k _" options works, I can connect clients. e.g.

$ pm2 start /opt/rustdesk-server/hbbs -- -r 192.168.1.10
$ pm2 start /opt/rustdesk-server/hbbr

Whilst starting hbbs with the "-k _" option also works:

$ pm2 start /opt/rustdesk-server/hbbs -- -r 192.168.1.10 -k _

However, hbbr does not like it....

$ pm2 start /opt/rustdesk-server/hbbr -k _
[PM2][WARN] Expect "kill_timeout" to be a typeof [object Number], but now is [object String]
[PM2][ERROR] Expect "kill_timeout" to be a typeof [object Number], but now is [object String]

Expected behavior

hbbr starts without error using the "-k _" option.