Storage: TypeError: self._dbInfo is null

Hello, i have problem
When i save my data to storage: set(’…’, ‘…’) an then i can get the data only once.

When i get data more than once i see error: TypeError: self._dbInfo is null

Code:
this.storage.get(‘category’).then((value) => {
this.getCat = true;
console.log("Category: " + value);
this.category = JSON.parse(value);
}).catch((err) => console.log(err));