[20:27:25] <+Wastl2> According to modtweaker's source, it's trying to access a ThaumcraftApi.recipes, which does exist.
[20:27:33] <+Wastl2> Uh...
[20:27:35] <+Wastl2> Too early.
[20:27:46] <+Wastl2> It's trying to access a ThaumcraftApi.recipes field, which does NOT exist.
[20:29:41] <+Wastl2> Neither in Azanor's ThaumcraftAPI nor in modtweaker's copy of that.

encountered via using this http://pastebin.com/i500aeB2

The error should not have any effects on the functionality of modtweaker, its only an old chunk of code which is not used anymore, but is now reported because of the increased logging.

Anyway, thanks for reporting. The old code will be removed in the next release.