bug fix, only call phetioEvents.end if a legal and usable tandem, https://github.com/phetsims/phet-io/issues/1245 https://github.com/phetsims/phet-io/issues/1235
bug fix, only call phetioEvents.end if a legal and usable tandem, https://github.com/phetsims/phet-io/issues/1245 https://github.com/phetsims/phet-io/issues/1235

phetsims/sun,phetsims/sun,phetsims/sun