Crash app

[hungdev]

If we dont pass height into dropdownStyle , and the dropdown doesn't show in bottom then it will crash because
Math.max(0, this._buttonFrame.y - dropdownHeight) and dropdownHeight = "auto" then top position is Math.max(0, this._buttonFrame.y - "auto") = NaN. The app will crash.
temporary solution is remove dropdownHeight from this line: https://github.com/siemiatj/react-native-modal-dropdown/blob/master/components/ModalDropdown.js#L335

[zxar7]

I faced this issue when I had 3 dropdowns and I tried opening the 3rd one. I had set the height in dropdownStyle to auto. It looked the the height was set to some minimum that was not based on the number of options I was sending in.
I was able to overcome this by specifying the height by multiplying my minHeight with the number of options.