[PR #1558] Fixed bug and typo in AFError implementation.

Source/AFError.swift

@@ -144,7 +144,7 @@ extension AFError {
     /// Returns whether the AFError is a parameter encoding error. When `true`, the `underlyingError` property will
     /// contain the associated value.
     public var isParameterEncodingError: Bool {
-        if case .multipartEncodingFailed = self { return true }
+        if case .parameterEncodingFailed = self { return true }
         return false
     }
 
@@ -297,8 +297,8 @@ extension AFError.ResponseValidationFailureReason {
 
     var responseContentType: String? {
         switch self {
-        case .unacceptableContentType(_, let reponseType):
-            return reponseType
+        case .unacceptableContentType(_, let responseType):
+            return responseType
         default:
             return nil
         }