Don't forward events to uninitialized EventPlugin implementations
Don't forward events to uninitialized EventPlugin implementations

Another part of fixing #2090

Jaesin/OctoPrint,Jaesin/OctoPrint,Jaesin/OctoPrint,foosel/OctoPrint,JackGavin13/octoprint-test-not-finished,foosel/OctoPrint,JackGavin13/octoprint-test-not-finished,JackGavin13/octoprint-test-not-finished,foosel/OctoPrint,JackGavin13/octoprint-test-not-finished,foosel/OctoPrint,Jaesin/OctoPrint