search plugin: Cannot read property 'toString' of undefined

[barthalexander]

Hey,
first of all, thanks for this great addon.

I'm using the search plugin and on each time I initialize the tree, i get this error named in the title.
The problem is on line 7261:
if(str === false || $.trim(str.toString()) === "") { return this.clear_search(); }

I think you have also to check for 'undefined'.