In this part of the error log it says: "The RF API that is being used (1.5.0 from (guessing) null) differes from that that is reported as being loaded (1.8.9R1.2.0B1 from mcjtylib-1.1x-2.5.3.jar). It is a supported version, but that difference may lead to problems. This may (look up the meaning of 'may' in the dictionary if you're not sure what it means) have caused the error. Try reproducing the crash WITHOUT this/these mod(s) before reporting it.", try finding this specific mod, turn it off or remove it temporarely and see if it fixes the problem. If it does I do not know how to make it work with the mod but at least it won't crash anymore right then.