Retrieving array data from memory lead to the following error: Byte array instantiated with invalid type '$.Toybox.Lang.String'

In one of my app i store an array of strings into the device memory but then, when i get them back using the following:

MemItemsStoredArray = new Array<String>[MemItemsTotalIndex];
......
MemItemsStoredArray=Storage.getValue("MemItemsArrays");

I check for null values or empty strings: using the following simple loop "for"

for (var j=0;j<MemItemsIndex;j++)
{

if ( (MemItemsStoredArray[j]==null)) {MemItemsStoredArray[j]="-";}
else if (MemItemsStoredArray[j].equals("")) {MemItemsStoredArray[j]="-";}
.....
.....

The compiler says that MemItemsStoredArray[j]="-"; is an error due: Byte array instantiated with invalid type '$.Toybox.Lang.String'

This is only with SDK 8.3.0. It was perfect on the previous SDK

Please help