var something = ['one', 'two', 'three'];

// some more code

// then woops!
something = null;

$.each(something, function(){
  console.log(this);
});

The code above will cause a js error on something.length.

to fix it you need do do the following... maybe this check should be incorporated?

var something = ['one', 'two', 'three'];

// some more code

// then woops!
something = null;

if (something != nul) {
  $.each(something, function(){
    console.log(this);
  });
}