When one is serving the Galactic Empire in the Star Wars galaxy, it's generally a good idea to never, ever get on Darth Vader's bad side. The best thing to do is avoid giving the Dark Lord bad news, thereby failing to meet his expectations and orders. When Lord Vader served his Emperor as his apprentice and second in command, there was a revolving door of officers and subordinates that Vader would work though. He would kill them if they ever told him bad news or if he found their work to be unsatisfactory. In one short story from Marvel Comics, Vader's wrath even extended to the smallest of those in service to the Empire.
The short story titled "No Good Deed..." (from writer Chris Eliopoulus with art from Jordie Bellaire) was featured at the end of 2017's Darth Vader #1 . The story follows Darth Vader as he deals with a particularly frustrating series of events throughout the day. First, he orders his mouse droid to prepare his meditation chamber when he gets a transmission from one of his officers. He tells Lord Vader that he is unable to organize an assault by the deadline Vader set, resulting in Vader killing the officer for his incompetence using the Force. He then orders his mouse droid to continue preparing his chamber. However, another officer enters Vader's quarters, informing him that they just deployed 10,000 troops to a nearby system. Sadly, the officer just sealed his fate as Vader had ordered 50,000 troops, paying for his mistake with his life. Vader commands his droid to dispose of the body and continue preparing his chamber, desiring no more interruptions.
However, before the droid can close the door, another officer arrives to inform Darth Vader that they were unable to repair his personal TIE Fighter, which leads to his death as well, and the droid clears that body from the room in similar fashion. Vader, growing ever more impatient, demands that his chamber be ready at once, and the droid scrambles to complete its task. Thankfully, the droid is successful and Vader seems satisfied, sharing his anger over the officers' failures with the only servant who managed to meet his expectations.
Unfortunately, not even the mouse droid's success with the meditation chamber could save it from accidentally bumping into Lord Vader himself. For its transgression, Lord Vader destroys the mouse droid entirely, presumably under his boot. However, he does finally sit in his meditation chamber, seemingly content that it was ready for him in any case, as he could now relax with no further incompetence to interrupt him.
It's a fairly humorous story featuring the Dark Lord, especially considering that not even a seemingly insignificant mouse droid can escape Vader's rage. In Vader's eyes, no amount of prior success is enough if it's followed by failure or imperfection. The story's made even funnier considering Vader had just confided in the little droid that it was the only one on the ship who hadn't tested him, and yet that statement changes immediately after those words are spoken. It's the same vibe as Scar from the Lion King when he's dealing with the hyenas, resigning himself to the fact that he's surrounded by idiots. Regardless, Darth Vader won't tolerate failure from anyone in the Star Wars universe, especially those under his command.