Error: Target must be an event emitter

Hey,

I'm having this weird problem that I can't get anything into edit mode suddenly anymore due to this dojo related script error I'd guess? I'm using a fairly fresh install of the latest Episerver packages from nuget (not pre-release though). The CMS seems to otherwise work and the site opens as usual, all help is accepted :).

epi.js:2 Error: Target must be an event emitter
at _1f9 (dojo.js:15)
at Function.on.parse (dojo.js:15)
at on (dojo.js:15)
at _d95.start (widgets.js:2)
at .<anonymous> (widgets.js:2)
at dojo.js:15
at when (dojo.js:15)
at _b52.initialize (widgets.js:2)
at .<anonymous> (epi.js:2)
at dojo.js:15