feat: add error messages to error flashes

[sutterj]

Pull Request

Proposed Changes

• Closes Display specific error message in error flash #128
  • Add error messages to error flashes
  • Display error messages if error when creating, editing, and deleting mirrors

Readiness Checklist

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Reviewer

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[sutterj]

Currently there is some handling in the create procedure to make a "pretty" message if one already exists:

This is the only error that has this, so is it worthwhile to do this for the other procedures or is that too specific/tedious because of the number of possible errors:

[zkoppert]

Currently there is some handling in the create procedure to make a "pretty" message if one already exists:

This is the only error that has this, so is it worthwhile to do this for the other procedures or is that too specific/tedious because of the number of possible errors:

@ahpook thoughts?

[ajhenry]

looks good from an engineering pov

[ahpook]

Hmmm. How many potential other messages are we looking at? The json barf is pretty ugly ...

Is the format predictable enough to extract the message field and pretty-print that with a generic "Failed to create mirror. Error was: " banner?

[sutterj]

I'm not really sure how many, but I would guess that the name conflict one is probably the most common and that one is already covered. I would imagine that the API is consistent and returns a message field though and that would be easy to add to the banner by itself.