EventBus.on throws when callback is an async function or generator

[xcrzx]

Describe the Bug

Due to the bug in min-dash (bpmn-io/min-dash#10) when an async function is passed as the second argument to EventBus.prototype.on (https://github.com/bpmn-io/diagram-js/blob/master/lib/core/EventBus.js#L124) it throws new Error('priority must be a number').

Steps to Reproduce

eventBus.on('foo', async function() {});

Throws: Error: Uncaught [Error: priority must be a number]

Expected Behavior

It doesn't throw.

Environment

Please complete the following information:

• Browser: Chrome 74
• OS: OS X
• Library version: 3.3.0

[barmac]

This will be fixed with next min-dash release and update.