FATAL on malformed zbase on checkmessage RPC

[gdassori]

Issue and Steps to Reproduce

$ lightning-cli checkmessage -k message=msg zbase=wrong
lightning-cli: reading response: socket closed

from the logs:

lightningd: lightningd/signmessage.c:59: from_zbase32: Assertion `len == tal_bytelen(u8arr)' failed
lightningd: FATAL SIGNAL 6 (version v0.11.1)
0x55b9b1b4e617 send_backtrace
[...]

getinfo output

   "version": "v0.11.1",

[vincenzopalazzo]

This happens because of this parameter zbase=wrong this should never happens, but I agree that the cmd line should be more user friendly!

I will try to look inside it