i think you need php5.4 to run 388 but you CAN still run 387 on php5.4 although, having issues with addons is more of that said addon having the php issue, and most of the time its an easy fix.
@mdawd - I tried to get this error although I couldn't replicate it, and those lines... nothings poping out at me as anything that would be an issue =/
however, have you tried using
https://vborg.vbsupport.ru/showthread.php?t=218350 it doesn't have the ajax feature, but it has ALOT more options, and I'd say its a better product (just my 0.02$)