Short answer:
Use of the "-qd" ?(quiet, don't decode as APRS) ?command line option will now suppress that error message.
The fix is now in the "dev" branch. ?Just ignore the error message until you get a newer version. ?It doesn't hurt anything.
Explanation:
When using APRS, the first character of the information part of the field is called the "data type indicator." ?
"T" indicates telemetry. ?In this case the following character should be "#". ?This message would be appropriate when using APRS. ?
However, it looks like you are using traditional packet radio. ?Here the UI frames (broadcasts, not to a particular station) can have any text without any formatting rules.
