Disable the weakauras in that group one by one (disable, test, if it stops that is the one, if not, re-enable it and repeat with the next one) until you find the one that is the error. Then either remove it or figure out why it wants the variable name populated and solve it.
Some causes are: you don't have the right talent selected, you have to do something within the weakaura to get it to recognize that specific weakaura, or it just does not have sanity checks in case a variable is nil (blank)
Once you find the offending aura, you can always post the error and the weakaura to the page you got it from on wago so that author knows there is a problem.