API mostly working, starting to work on webapp

Models/RequestError.cs

@@ -0,0 +1,34 @@
+namespace ComiServ.Models
+{
+    public class RequestError
+    {
+
+        public static RequestError InvalidHandle => new("Invalid handle");
+        public static RequestError ComicNotFound => new("Comic not found");
+        public static RequestError CoverNotFound => new("Cover not found");
+        public static RequestError PageNotFound => new("Page not found");
+        public static RequestError FileNotFound => new("File not found");
+        public string[] Errors { get; }
+        public RequestError(string ErrorMessage)
+        {
+            Errors = [ErrorMessage];
+        }
+        public RequestError(IEnumerable<string> ErrorMessages)
+        {
+            Errors = ErrorMessages.ToArray();
+        }
+        public RequestError And(RequestError other)
+        {
+            return new RequestError(Errors.Concat(other.Errors));
+        }
+        public RequestError And(string other)
+        {
+            return new RequestError(Errors.Append(other));
+        }
+        public RequestError And(IEnumerable<string> other)
+        {
+            return new RequestError(Errors.Concat(other))
+                ;
+        }
+    }
+}