[varInspector] improved test and reload in case of a lib reset

Author: jfbercher

src/jupyter_contrib_nbextensions/nbextensions/varInspector/main.js

@@ -144,8 +144,12 @@ function html_table(jsonVars) {
 
     function code_exec_callback(msg) {
         var jsonVars = msg.content['text'];
-        if (jsonVars == undefined) varInspector_init() 
-        //means that msg.text is undefined, that is var_dic_list was cleared ==> need to retart the enxtesnion
+        var notWellDefined = false;
+        if (msg.content.evalue) 
+            notWellDefined = msg.content.evalue == "name 'var_dic_list' is not defined" || 
+        msg.content.evalue.substr(0,28) == "Error in cat(var_dic_list())"
+        //means that var_dic_list was cleared ==> need to retart the extension
+        if (notWellDefined) varInspector_init() 
         else $('#varInspector').html(html_table(jsonVars))
 
         require(['nbextensions/varInspector/jquery.tablesorter.min'],