I am quite confused as to when to use the words show and show up.
I have been thinking show is an action conducted by a person, and show up is used
when someone appeared, like "He has been showing up recently in the party."
However, I have seen someone saying "an error message keeps showing up", and became confused since then because I have been using the expression "an error message keeps showing"
I've become curious about the exact usage of those words in different situations.
Which word do I have to choose in that situation?
Is it "an error showing up" or "an error showing" ?