refactor(middlewares): move MiddlewareError from crate::utility to crate::middlewares

src/middlewares/error.rs

@@ -0,0 +1,19 @@
+use serde::{Deserialize, Serialize};
+use std::fmt::Display;
+use std::fmt::Write;
+
+/// Server response to errors within Middleware.
+#[derive(Serialize, Deserialize)]
+pub struct MiddlewareError<T: Display> {
+    code: T,
+    message: String,
+}
+
+impl<T: Display + Serialize> MiddlewareError<T> {
+    pub fn new(code: T) -> Self {
+        let mut message = String::new();
+        write!(&mut message, "{}", code).unwrap();
+
+        Self { code, message }
+    }
+}