I am not an insurance expert. You should definitely check with the insurance company you are insured by or are thinking of purchasing. If you go to the Idea link on your home page for “Liability Insurance”, there are brief statements of coverage and you can contact the company of more information.
Whenever I ask these types of questions of any support service business, I ask for the answer in writing. Verbal statements are worthless unless you have witnesses.
My policy read that I am covered for anything that I do that is determined to have caused injury or anything that I didn’t do and should have done to prevent injury. If that is what you mean by “errors and omissions”.