`errdefer` capture is an error union instead of error set when the function returns an `@errorCast`ed error

[xdBronch]

Zig Version

0.14.0-dev.107+e03026507

Steps to Reproduce and Observed Behavior

pub fn main() error{a}!void {
    errdefer |err| @compileLog(@TypeOf(err));
    return @errorCast(@as(anyerror!void, error.a));
}

@as(type, error{a}!void)

Expected Behavior

the captured err should be an error{a}