This is really odd. You could turn on the developer tools in the browser (Ctrl -Shift - I) and possibly see what is causing the error/crash in the console. When I click on a property field the console shows that code in the scripts.js file is executing. Is this from a windows client PC? Seems like the problem is in the client somewhere and not on the server, because editing a property doesn't send anything to the server.
You could work around this by using the Pre Execution function.
function f() {
this.chartDefinition.valuesVisible = true;
}
I usually do all my chart settings in the pre execution function. It's easier to see what settings were overridden from the default settings.