copied Pubnub.cs file with error callback from C# core
copied Pubnub.cs file with error callback from C# core

grokify/c-sharp,grokify/c-sharp,grokify/c-sharp,grokify/c-sharp,marceloinacio/c-sharp,marceloinacio/c-sharp,marceloinacio/c-sharp,marceloinacio/c-sharp,marceloinacio/c-sharp,grokify/c-sharp