The only base-10 integers OPEN and ERROR such that each letter represents one distinct decimal digit are OPEN = 8276 and ERROR = 74484. 74484 is 9 times 8276, thus A=9 or T=9.

Given the partial product REAPS as a multiple of OPEN with each letter representing one distinct digit REAPS would need be 41380 or 57932, yet with OPEN=8276 and ERROR = 74484,
REAPS would need be of the form 47A2S. Neither 41380 nor 57932 is of the form 47A2S, thus there is no solution with the givens.