file corruption after first write

this is my scenario:


as you see in my code I save user location lat lng time in an array and save them in the database then read them and make array like below:
`[ [ lat, lng, time ], [ lat, lng, time ] ]`
I stringify the array and save it to the location.json file.
after my array length increase, the location.json file gets corrupted like this:


can anyone help me with this?
thanks