GeoJSON.Collision throws `Cannot read property` errors

[5310]

It seems that the GeoJSON version of this addon can't find the extended properties on itself. Simply calling L.geoJSON.collision(...) throws

Uncaught (in promise) TypeError: Cannot read property 'push' of undefined
    at NewClass.addLayer (collision.js:26)
    at NewClass.addData (GeoJSON.js:127)
    at NewClass.addData (GeoJSON.js:104)
    at NewClass.initialize (GeoJSON.js:89)
    at NewClass.initialize (collision.js:9)
    at new NewClass (Class.js:22)
    at Function.L.geoJson.collision (collision.js:240)
    at main.js:27

I noticed there's only ever been one issue regarding GeoJSON on this repository, the one that added conditional calling of the parent constructor if the parent class was GeoJSON. But it doesn't seem to make any difference either way whether that patch is used or not.