When things go wrong
No matter how experienced or learned someone is, how many resources they have, how many measures they take, accidents and mistakes are inescapable. What defines a good musician isn't the absence of hiccups or errors, but rather, how they react to them.
Take as an example this rendition of Queen's quintessential song, Bohemian Rhapsody, played during a concert in Caracas, Venezuela, back in 1981.
Even if you aren't a fervent fan of Queen, it's highly likely that you've listened to this song enough times to tell something goes wrong at the 01:40 mark. Brian May works around the issue to play the solo for that part, but by 02:04, he changes the melody completely. The image isn't that clear, but apparently he missed his cue and broke one of his strings immediately after.
Observe how he doesn't freeze, doesn't stop or reacts in a visibly panicked way. His fellow band members do look slightly confused while they understand what happened, but this doesn't prevent them from playing their...