[§658B-13]  Supplementary general principles
of law.  Unless displaced by particular provisions of this chapter, the
principles of law and equity, including the law merchant, and the law relative
to capacity to contract, principal and agent, estoppel, fraud,
misrepresentation, duress, coercion, mistake, bankruptcy, or other validating
or invalidating causes supplement its provisions. [L 1990, c 50, pt of §1]