Panic when no arguments passed via `HELLO` command

[olvap80]

Describe the problem

Command without parameters leads to cryptic runtime error when called without parameters and developer skills are required to find out what is really wrong:

HELLO
panic: runtime error: slice bounds out of range [6:5]

goroutine 1 [running]:
github.com/arduino/pluggable-discovery-protocol-handler/v2.(*Server).Run(0xc0000f8000, 0xee7158, 0xc0000d8000, 0xee7178, 0xc0000d8008, 0xf96120, 0x0)
        /go/pkg/mod/github.com/arduino/pluggable-discovery-protocol-handler/v2@v2.0.2/discovery.go:135 +0x73f
main.main()
        /home/build/main.go:39 +0xfd

To reproduce

Issue command without parameters

Expected behavior

User friendly error message is expected with direct reference to https://github.com/arduino/serial-discovery

serial-discovery version

serial-discovery Version: v1.3.2 Commit: c5cf4d8 Date: 2022-02-22T08:48:19Z

Operating system

Windows

Operating system version

Windows 10

Additional context

The issue was discovered when trying to use serial-discovery tool as a part of the Arduino IDE

Issue checklist

• I searched for previous reports in the issue tracker
• I verified the problem still occurs when using the latest version
• My report contains all necessary details

[cmaglie]

Thanks for the bug report @olvap80!

I'm quite surprised this bug went unnoticed for so long... (I mean, the first thing someone will try is to run the HELLO command without parameters I guess).

I've prepared a fix here #33, if you want to give it a try.

[cmaglie]

Fixed in v2.1.1