qtip('disable') fails if tooltip not rendered before

[bornste]

If a qTip wasn't rendered and $('.selector').qtip('disable') is called the script fails with the error 'Cannot call method 'hasClass' of null'. If calling $('.selector').qtip('disable', true) it works as expected.

The cause is that 'this.tooltip' is accessed in PROTOTYPE.disable without checking if the tooltip was rendered.