Is immediately reporting errors at work—whether minor or major—considered a sin for which a person will be held accountable by Allah?

If the intention behind the action is to monitor people in order to alert those who err and to repel evil from Muslim society, then there is no sin in informing the competent authorities about it. However, if the intention is to monitor people, spy on them, and report them to those who oppress them, then this is forbidden and is considered participation with the oppressor in their oppression.