Allow viewing all computed error variants for anyerror function return catch captures

[sno2]

Hello, it would be amazing if we could view all computed error variants in the popup for the captured error. I do know that zig has some way to get the error variants for a function as shown by running the following program:

const E = error{ A, B, C };

fn magicBox(n: u8) !u8 {
    return switch (n) {
        0 => error.A,
        1 => error.B,
        2 => error.C,
        else => n,
    };
}

pub fn main() !void {
    magicBox(5) catch |e| switch (e) {};
}

Gives us errors for each of the unhandled error variants in the switch:

./example.zig:15:27: error: error.A not handled in switch
    magicBox(5) catch |e| switch (e) {};
                          ^
./example.zig:14:21: note: referenced here
pub fn main() !void {
                    ^
/opt/compiler-explorer/zig-0.9.0/lib/std/start.zig:553:40: note: referenced here
            const result = root.main() catch |err| {
                                       ^
./example.zig:15:27: error: error.B not handled in switch
    magicBox(5) catch |e| switch (e) {};
                          ^
./example.zig:15:27: error: error.C not handled in switch
    magicBox(5) catch |e| switch (e) {};

Personally, I would like it if when you scrolled over the captured e, it would show something like error{ A, B, C } which includes all of the variants.

I know this would take a bit of work, and I don't have time right now to contribute. But, it would be great so I'll just mark it down here as a wish in a bottle until I possibly attempt to implement it. Thanks

[nektro]

blocked on #552