src/Tools/VSCode/src/preview_panel.scala

           resources.get_model(file) match {
             case Some(model) =>
               val snapshot = model.snapshot()
               if (snapshot.is_outdated) m
               else {
-                val context = Presentation.html_context()
-                val document = Presentation.html_document(resources, snapshot, context)
+                val html_context = Presentation.html_context()
+                val document = Presentation.html_document(resources, snapshot, html_context)
                 channel.write(LSP.Preview_Response(file, column, document.title, document.content))
                 m - file
               }
             case None => m - file
           }