flush stdout and stderr in notebook eval

Author: pfitzseb

scripts/packages/VSCodeServer/src/serve_notebook.jl

@@ -25,11 +25,12 @@ function notebook_runcell_request(conn, params::NotebookRunCellArguments)
                 error_type = string(typeof(inner_err))
 
                 try
-                    st = stacktrace(bt)
-
                     error_message_str = Base.invokelatest(sprint, showerror, inner_err)
                     traceback = Base.invokelatest(sprint, Base.show_backtrace, bt)
 
+                    flush(stdout)
+                    flush(stderr)
+
                     return (success = false, error = (message = error_message_str, name = error_type, stack = string(error_message_str, "\n", traceback)))
                 catch err
                     return (success = false, error = (message = "Error trying to display an error.", name = error_type, stack = "Error trying to display an error."))