feat: Add a new ErrorHandlerWithContext

[tomscholz]

This commit adds a new error handler, which is passed the
current context, so that you can add custom redirects or even
other kinds of responses. For example:

e.Use(middleware.JWTWithConfig(middleware.JWTConfig{
	SigningKey: []byte("secret"),
	TokenLookup: "query:token",
	ErrorHandlerWithContext: func(err error, c echo.Context) error {
		// do stuff with context and err
		switch err.(type) {
		case jwt.ValidationError:
			return c.Redirect(http.StatusSeeOther, "/login")
		}
		return err
	},
}))

What needs to be done, to get this merged?

[tomscholz]

It seems like the build is failing because the script ran into some ratelimiter of the googleapi. If someone with access to the travis-ci project could retrigger the build. That would be neat!

[tomscholz]

Bump

[vishr]

@tomscholz Can this be achieved via a custom http handler?

[TomLiu-GitHub]

Somebody seems to think the same as me.

[vishr]

@TomLiu-GitHub, @tomscholz I can understand the sentiment but if you look at this change, it should/can be applied to all the middleware, isn't it?

[horrorhorst]

@vishr after a quick look I don't see this change necessary for all middlewares, but if the middleware has an option for a custom error handler, it can be useful and should be evaluated

[vishr]

For v5, I would like this to be merged with JWTErrorHandler.