Required Information

• DietPi version:

G_DIETPI_VERSION_CORE=8
G_DIETPI_VERSION_SUB=22
G_DIETPI_VERSION_RC=3
G_GITBRANCH='master'
G_GITOWNER='MichaIng'

• Distro version | bookworm 1
• Kernel version | Linux rpi-uk 6.1.21+ #1642 Mon Apr 3 17:19:14 BST 2023 armv6l GNU/Linux
• SBC model | RPi B (armv6l)
• Power supply used | 5.1V 2A Apple
• SD card used | SanDisk SD from September 2011

Steps to reproduce

1. Install kitty terminal on your desktop computer
2. SSH into DietPi through kitty +kitten ssh <user>@<ip>
3. Run sudo dietpi-update

Expected behaviour

• Update system or say it is up to date

Actual behaviour

 DietPi-Update
─────────────────────────────────────────────────────
 Phase: Checking for available DietPi update

tput: unknown terminal "xterm-kitty"
/boot/dietpi/func/dietpi-globals: line 267: ( 59 + 5 ) /  : syntax error: operand expected (error token is "/  ")

Extra details

I noticed this when I was updating DietPi, so I tried to set export TERM='dumb' but then it didn't come up with the updating UI so I had to get the keyboard out, plug it into a monitor and update it from there.
This issue potentially has some relation to #5347, running

/boot/dietpi/func/run_ntpd 1

still gives

/boot/dietpi/func/dietpi-globals: line 267: ( 58 + 5 ) /  : syntax error: operand expected (error token is "/  ")