[bug]: unhandled ZLE widget errors when using zsh over serial console

[agorgl]

Describe the bug

When starting zsh on a serial console session (e.g. in a VM with console=ttyS0 in kernel parameters and attaching with virsh console) I get these error/warning lines in the output:

zsh-syntax-highlighting: unhandled ZLE widget '^[[3~'
zsh-syntax-highlighting: unhandled ZLE widget '\C-W'
zsh-syntax-highlighting: unhandled ZLE widget '^?'

With the same configuration over a normal (non-serial console) tty session they do not appear.

Steps to reproduce

1. Start a virtual machine with console=ttyS0 in kernel parameters
2. Attach to the above virtual machine with virsh console
3. Login and make a minimal .zshrc that sources zdharma-continuum/fast-syntax-highlighting plugin
4. Run zsh

Expected behavior

To not see the above errors

Screenshots and recordings

No response

Operating System & Version

linux-gnu | pc | x86_64 | x86_64 | x86_64 unknown

Zsh version

zsh 5.9 (x86_64-pc-linux-gnu)

Terminal emulator

vt220

If using WSL on Windows, which version of WSL

None

Additional context

No response

[agorgl]

It also seems that launching zsh with TERM=xterm-256color zsh from tty does not produce these errors, while leaving the default TERM=vt220 zsh does produce them