Add ATProtoError

Tis is the best exception protocol that all custom errors
will conform to.

Author: MasterJ93

Sources/ATProtoKit/Errors/ATProtoError.swift

@@ -7,8 +7,10 @@
 
 import Foundation
 
+public protocol ATProtoError: Error {}
+
 /// The base exception class for ATProtoKit.
-public enum ATProtoError: Error, Decodable {
+public enum ATAPIError: ATProtoError, Decodable {
     /// Represents a bad request error (HTTP 400) with an associated message.
     /// - Parameter message: The message received along side the error.
     case badRequest(message: String) // Error 400
@@ -105,3 +107,9 @@ public enum ATProtoError: Error, Decodable {
         case message
     }
 }
+
+/// An error type related to ``ATImageProcessable``..
+enum ATImageProcessingError: ATProtoError {
+    /// The image's file size can't be lowered any further to fit the target file size.
+    case unableToResizeImage
+}