If you specify an invalid research in some methods like Research.addSibling or Research.addPrereq as a second parameter, Thaumcraft accepts it blindly, but when you open the Thaumonomicon, game crashes. While it is a TC issue, it would be good if ModTweaker can prevent it with validating research keys by matching it to a list of existing research keys. TC not prepared for add wrong keys and this is kind of intended, however it handles it very poorly.