After upgrading to RN0.29 and RN0.30 I started getting this unhelpful exception:
'One of the sources for assign has an enumerable key on the prototype chain'
I traced this back to the use of spread syntax in jsx component calls. The error would go away if I specified the individual attributes explicitly. Props in this case is a regular object supplied through an enclosing method (not a jsx this.props)
<RouteScreen
      {...props}
      pathVariables={pathVariables}
I'm not sure why this suddenly stopped working. Only seems to happen in some cases. Any suggestions?