Warning [vue-hammer] invalid event type: pressup

[HoraceKeung]

Directive v-hammer:pressup="onPressUp" works as expected, but there is warning: [vue-hammer] invalid event type: pressup showing up when the web app loads.

[tommitytom]

I'm also getting a similar error to this. If I use the following code I get no warning, but it does not work:
v-hammer:pan.start="onPanStart"
However if I use the following code it works fine,
v-hammer:panstart="onPanStart"
But I get the following warning:
[vue-hammer] invalid event type: panstart

I get the warning for every directive that has 2 parts (panstart, panend etc, but not pan)