add some api helpers

x/errors/context_error_handler.go

@@ -0,0 +1,17 @@
+package errors
+
+import "github.com/kataras/iris/v12/context"
+
+// DefaultContextErrorHandler returns a context error handler
+// which fires a JSON bad request (400) error message when
+// a rich rest response failed to be written to the client.
+// Register it on Application.SetContextErrorHandler method.
+var DefaultContextErrorHandler context.ErrorHandler = new(jsonErrorHandler)
+
+type jsonErrorHandler struct{}
+
+// HandleContextError completes the context.ErrorHandler interface. It's fired on
+// rich rest response failures.
+func (e *jsonErrorHandler) HandleContextError(ctx *context.Context, err error) {
+	InvalidArgument.Err(ctx, err)
+}