It’s hard to know whether these log entries are you (Can you share the IP address your client is running from?) but there are some recent entries matching this returned error that have some additional context:
unable to JSON parse registration: json: cannot unmarshal array into Go struct field Registration.agreement of type string
IFF this is you, that would suggest that the registration object your ACME client is sending has an “agreement” field that isn’t a string with the current Let’s Encrypt subscriber agreement URL, but an array of some sort.
I’m not proficient with PHP to try and diagnose the root cause, I recommend you raise this as a bug report with the authors of Lescript after verifying that this error is the one being caused by your requests.