Fixed linking reference failure

Author: v-alcherepen

samples/features/reporting-services/ssrs-migration-rss/ssrs_migration.rss

@@ -934,7 +934,10 @@ End Sub
 
 'Helper function to link snk reference with relative paths
 Function GetSnkPathRef(srcPath As String) As String
-	Dim snkPath = srcPath.Remove(0, srcSiteUrl.LastIndexOf("/"))
+	Dim snkPath = srcPath
+	If srcSiteUrl isNot Nothing
+		snkPath = srcPath.Remove(0, srcSiteUrl.LastIndexOf("/"))
+	End If
 	Return snkPath
 End Function