fix issue if bad part name is given it shows the default head

src/main/java/cc/fascinated/model/response/impl/InvalidPartResponse.java

@@ -0,0 +1,11 @@
+package cc.fascinated.model.response.impl;
+
+import cc.fascinated.model.response.Response;
+import org.springframework.http.HttpStatus;
+
+public class InvalidPartResponse extends Response {
+
+    public InvalidPartResponse() {
+        super(HttpStatus.NOT_FOUND, "Invalid part name.");
+    }
+}