It would usually be a mistake to assume that the way to build a strong relationship would be to reveal the most private details about yourself when first making contact with another person.
I saw the above sentence in a exam passage.
I learned we can use participle clauses when the participle and the verb in the main clause have the same subject.
But the above sentence does not look like that. Is it a correct sentence? If so, what is the subjects of the participle and the main verb?