Prevent editor to break after first error
Prevent editor to break after first error

If a spec is wrong, `ved.view` becomes an instance of Error. The code
trying to execute `ed.view.destroy()` fails, and it becomes impossible
to parse a valid spec again unless one refreshes the HTML page.

jlove29/vega-editor,vega/vega-editor,jlove29/vega-editor,vega/vega-editor,jlove29/vega-editor,vega/vega-editor