refactor: remove some duplicated code

routes/_middleware.ts

@@ -0,0 +1,25 @@
+//routes/middleware-error-handler/_middleware.ts
+import { MiddlewareHandlerContext } from "$fresh/server.ts";
+import { DomainError } from "@lib/errors.ts";
+
+export async function handler(
+  _req: Request,
+  ctx: MiddlewareHandlerContext,
+) {
+  try {
+    ctx.state.flag = true;
+    return await ctx.next();
+  } catch (error) {
+    console.error(error);
+
+    if (error instanceof DomainError) {
+      return new Response(error.statusText, {
+        status: error.status,
+      });
+    }
+
+    return new Response("Internal Server Error", {
+      status: 500,
+    });
+  }
+}