Cannot read property 'prototype' of undefined with primus-emitter

[VR99]

Using primus@7.0.2 and primus-emitter. Getting the following error.

var initialise = Spark.prototype.initialise;
^
TypeError: Cannot read property 'prototype' of undefined

[mrx8]

In case you did:
Primus.use("emitter", require('primus-emitter'));
try:
Primus.plugin("emitter", require('primus-emitter'));