IE implementation doesn't support putting null values (tested on IE11)
that's the output on IE console when putting null value:
\>> SCRIPT87: Invalid argument.
\>> File: localForage.js, line: 89, Column: 7
and to be more specific, that's the ouptut when putting null and undefined values from the console
<< localForage.setItem("item", null)
\>> Invalid argument.
<< localForage.setItem("item", undefined)
\>> undefined
note: getItem function (on asyncStorage) already returns null values when the req.result value is undefined. so this will not break the code, we still get null values on getItem function (getItem/setItem function on localStorageWrapper maybe need some changes)