fix bug with persisting event handler
fix bug with persisting event handler

andyh616/jsPsych,erikasf/jsPsych,andyh616/jsPsych,vergenzt/jsPsych,jspsych/jsPsych,jspsych/jsPsych,Scienthusiast/jsPsych,wolfgangwalther/jsPsych,erikasf/jsPsych,jspsych/jsPsych,jspsych/jsPsych,shamrt/jsPsych,msrresearch/jsPsych,shamrt/jsPsych,jodeleeuw/jsPsych,adrianoesch/jsPsych,adrianoesch/jsPsych,Scienthusiast/jsPsych,wolfgangwalther/jsPsych,vergenzt/jsPsych