What is the legal test for correcting errors in a will?

In the context of wills, Belobaba J., in Robinson Estate v. Rondel, confirmed that: 24 Where there is no ambiguity on the face of the will and the testator has reviewed and approved the wording, Anglo-Canadian courts will rectify the will and correct unintended errors in three situations: (1) where there is an accidental slip or omission because of a typographical or clerical error; (2) where the testator's instructions have been misunderstood; or (3) where the testator's instructions have not been carried out.