Proposal - Pretty print error structs in debugger page

[leandrocp]

I couldn't find such proposal in past issues/PRs so this one is a simple PoC to gather feedback if that's a good idea or not.

In short, currently the debugger page looks like this:

And the idea is to improve UX by displaying this:

Notes:

• It may get too long so a toggle link to show/hide details could help
• Pattern matching the error to pretty inspect it instead of calling Exception.message/1 seems okay to deal with some exceptions but it could get out of sync with Elixir stdlib if wording changes.

[josevalim]

It feels like we should just format the whole error message as <code>, because they are written with assumption they will be printed monospaced?

[leandrocp]

It feels like we should just format the whole error message as <code>, because they are written with assumption they will be printed monospaced?

Do you mean the error message from the original code? 🤔 The problem here is that Exception.message/1 does return a string with no line breaks, that's why I had to reformat as inspect(term, pretty: true, limit: :infinity)

[josevalim]

Let’s change Elixir to use pretty for this message and also change Plug to use code style for the error message :)

[leandrocp]

Gotcha. I can send a PR to Elixir and then update this one.

[leandrocp]

So that's how a simple message would like:

And how a long KeyError would like:

[josevalim]

I think we can keep the style closer to what you had: grey and smaller font. :)

[leandrocp]

I think we can keep the style closer to what you had: grey and smaller font. :)

For all error messages like the MatchError example above? Because they all share the same style.

[leandrocp]

That's how it would like, grey and smaller font:

A regular exception:

And KeyError with pretty: true:

[josevalim]

Perfect. Let's do said changes and for all error messages. :)

[josevalim]

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