When testing 4.2, my application tried to do a removeAll on an empty store and hit this error

Uncaught TypeError: Object [object Object] has no method 'removeRange'


PHP Code:
if (removeRange) {
data.removeRange(records.startremoveCount);

at row 72223 in ext-all-debug

data is a "Ext.util.LruCache" class and sure enough, this method doesn't exist on the class.