Bug 1875: Failure when canceling an authentication of an ad-hoc session from a workspace opened from command-line

https://winscp.net/tracker/1875
(cherry picked from commit 211928d3635c2554f309e278ca96f8bfde564a4c)

Source commit: 02db72d5146b1f7bdaa8f93ff9e4227bf8ad00f9

source/windows/TerminalManager.cpp

@@ -497,7 +497,10 @@ void __fastcall TTerminalManager::DisconnectActiveTerminal()
   OldQueue = reinterpret_cast<TTerminalQueue *>(FQueues->Items[Index]);
   NewQueue = this->NewQueue(ActiveTerminal);
   FQueues->Items[Index] = NewQueue;
-  ScpExplorer->Queue = NewQueue;
+  if (ScpExplorer != NULL)
+  {
+    ScpExplorer->Queue = NewQueue;
+  }
   delete OldQueue;
 
   ActiveTerminal->Disconnected = true;