Is a medical student who, out of ignorance, errs in estimating drug dosages or in answering a patient, liable for ضمان (guarantee/restitution) even if no harm is evident?

A doctor who is not proficient in their profession, if they cause damage to an organ or a life through their action or prescription, is sinful and is held liable for the consequences of their offense. As for a skilled doctor who errs in their professional judgment, they are held liable but are not sinful. Liability arises when actual harm occurs, not merely from the possibility of it.