The game crashed whilst rendering screen
Error: java.lang.ArrayIndexOutOfBoundsException: Index -1 out of bounds for length 129-

and a lot of other GUIs cause a crash

Edit: It seems to only crash upon the first time opening a specific interface

Could you post the full crash report along with the version of Minecraft and the version of Transparent?

Without further information or other bug reports, I can't fix this so I am assuming it to not be a problem. If anyone finds more information in the future, please create a new issue with a full crash report and the versions of the mods you are using.