question: An erroneous understanding of a fact or situation may only invalidate a state 's consent to a treaty if what is also true about the erroneous understanding ?
answer: formed the `` essential basis '' of the state 's consent
turker_answer: An erroneous understanding of a fact or situation may only invalidate a state 's consent to a treaty if it formed the essential basis of their consent
rule-based: An erroneous understanding of a fact or situation may only invalidate a state 's consent to a treaty if formed the `` essential basis '' of the state 's consent is also true about the erroneous understanding .