Added ServerErrorWithCode and updated comments

Author: Catalina Turlea

Sources/Base/OAuth2Error.swift

@@ -82,8 +82,11 @@ public enum OAuth2Error: Error, CustomStringConvertible, Equatable {
 	/// There is no delegate associated with the password grant flow instance.
 	case noPasswordGrantDelegate
 
-	case clientError(Int)
+	/// Generic client error 400<..500
+	case clientErrorWithStatus(Int)
 
+	/// Generic server error <=501
+	case serverErrorWithStatus(Int)
 
 	// MARK: - Request errors
 
@@ -275,7 +278,9 @@ public enum OAuth2Error: Error, CustomStringConvertible, Equatable {
 			return message ?? "The requested scope is invalid, unknown, or malformed."
 		case .serverError:
 			return "The authorization server encountered an unexpected condition that prevented it from fulfilling the request."
-		case .clientError(let statusCode):
+		case .serverErrorWithStatus(let statusCode):
+			return "The authorization server encountered an unexpected condition, returning \(statusCode)"
+		case .clientErrorWithStatus(let statusCode):
 			return "The authorization server returned \(statusCode)"
 		case .temporarilyUnavailable(let message):
 			return message ?? "The authorization server is currently unable to handle the request due to a temporary overloading or maintenance of the server."

Sources/Flows/OAuth2.swift

@@ -352,7 +352,7 @@ open class OAuth2: OAuth2Base {
 	/**
 	If there is a refresh token, use it to receive a fresh access token.
 
-	Does not remove the refresh_token in case of a failure. For client errors (400..<500), the callback will provide the status code in the .clientError(Int)
+	Does not remove the refresh_token in case of a failure. For client errors (4xx), the callback will provide the status code in the .clientErrorWithStatus(Int). For server errors (5xx), the callback provides the status code in .serverErrorWithStatus(Int)
 
 	- parameter params:   Optional key/value pairs to pass during token refresh
 	- parameter callback: The callback to call after the refresh token exchange has finished
@@ -366,11 +366,12 @@ open class OAuth2: OAuth2Base {
 				do {
 					let data = try response.responseData()
 					let json = try self.parseRefreshTokenResponseData(data)
-					switch response.response.statusCode {
-					case 500:
-						throw OAuth2Error.serverError
+					let statusCode = response.response.statusCode
+					switch statusCode {
 					case 400..<500:
-						throw OAuth2Error.clientError(response.response.statusCode)
+						throw OAuth2Error.clientErrorWithStatus(statusCode)
+					case 500...599:
+						throw OAuth2Error.serverErrorWithStatus(statusCode)
 					default:
 						throw OAuth2Error.generic("Failed with status \(response.response.statusCode)")
 					}