In working with more junior engineers I've always found they're scared to make mistakes. They're scared of causing an issue or breaking something that would reflect negatively on them. When they do cause an issue, you can see how badly it affects them. It's heartbreaking.
My usual response to them when they raise this concern or break something is to tell them not to worry, that I'll handle it, and to say that everyone has broken something at some time or another and you won't be the first or the last to do so. I usually accompany this with a personal anecdote surrounding one time or another where I've personally screwed up and caused some serious problems and lived to tell the tale.
I thought it'd be fun to find out what yours are...
I've got two to three that all happened in my first year in industry (a long time ago), but the main one that caused me the most panic was when I accidentally sent tens of emails out to production customers with fake orders on them. These customers received invoices for tens of thousands of pounds worth of product and immediately thereafter received 'reminder' notices (as that was the feature I was working on). Turns out, the 'fake' user data I was testing against wasn't so fake after all and the 'development' email service I was using actually had permissions to forward emails out into the real world. This was escalated to the CEO for him to personally contact the customers and offer his apologies for the mishandling of the data.
In hindsight, I don't think it was my fault. The 'fake' data shouldn't have been a copy of real user data and the development email service shouldn't have been allowed to forward emails out of the local domain. That didn't stop my heart falling into my stomach the instant I realised my mistake, however. I had no one tell me everything was fine, which is why I make it a point to now.