create a fcm error class

Author: Roy-Mao

lib/fcm/error.rb

@@ -0,0 +1,33 @@
+# frozen_string_literal: true
+
+module Fcm
+  # Custom Fcm errors
+  class Error < StandardError
+    ERROR_RESPONSE_400 = 'Only applies for JSON requests.'\
+    ' Indicates that the request could not be parsed as JSON,'\
+    ' or it contained invalid fields.'
+
+    ERROR_RESPONSE_401 = 'There was an error authenticating'\
+    ' the sender account.'
+
+    ERROR_RESPONSE_503 = 'Server is temporarily unavailable.'
+
+    ERROR_RESPONSE_50X = 'There was an internal error in the'\
+        ' FCM server while trying to process the request.'
+  end
+
+  # Raised on errors in the 400-499 range
+  class ClientError < Error; end
+
+  # Raised when Faraday returns a 400 HTTP status code
+  class BadRequest < ClientError; end
+
+  # Raised when Faraday returns a 401 HTTP status code
+  class Unauthorized < ClientError; end
+
+  # Raised on errors in the 500-599 range
+  class ServerError < Error; end
+
+  # Raised when Faraday returns a 503 HTTP status code
+  class ServiceUnavailable < ServerError; end
+end