I had the same problem a few days ago when developing a new driver for sestosenso2 focuser, which was caused by the LOG_ERROR function - too long argument was passed to the logger. Maybe the same issue ?
This is a build issue, there was a renaming of a function in base INDI library (tty_set_skywatcher_udp_format -> tty_set_generic_udp_format) and the nightly eqmod build seems to have been built with the old library version. So it should fix itself in a nightly or two. This is unfortunately a recurring issue when APIs change as there aren't versioned dependencies in place. When compiling yourself it's easy to avoid by always compiling the base INDI library first before 3rd-party drivers.