Breaking a taillight isn't usually going to get you fired, especially if no police report and nobody was towed away. Even if it went on your DAC report the longer you stay at the company that reported it to DAC the less impact it will have. Not every company reports to DAC and not every company reads your DAC report.
As a new driver you should avoid EVERYTHING, like scratching a trailer, hitting something on customer property, traffic tickets and traffic accidents like it will end your career, but some of these are just going to be small issues that stay within the company. My impression with new drivers is that they seem to just assume they wre going to get tickets, have accidents, and damage property like it's nothing. Your career isn't over, you may not even get punished.
JUST BE MORE CAREFUL, the next small incident could be an end to your current job. Don't just let stuff happen.
I had 2 similar preventable in my first month of being a solo driver. Both minor truck parking lot affairs such as described. Wasn't good, but it didn't end my career. And, I learned from them and haven't had to repeat those mistakes, yet (alittle over 2 years solo at this point).
Most important thing is to learn from them and adjust. I found I need to be more careful when it's dark and to focus on my task at hand instead of worrying about a million other details instead and not concentrate on driving and maneuvering, while I'm driving and maneuvering.