The "scale of terrifying" can range for many people depending on the past trauma or other things that have happened in their life to develop this phobia.

The phobia of making mistakes could possibly be OCD ( if you don't know what it stands for - Obsessive Compulsive Disorder ) which in this case might make you scared of intrusive thoughts or harming others in a physical and/or mental way. There is a specific term for this though, Atychiphobia which is the phobia of failure or making mistakes which is not directly harming others in a physical state it could cause you to worry about "harming" others in a mental state.