accessing dictionary data is not consistent

Indeed because it’s an associative array

You could basically consider it an array of keys and an array of values.  Search for key in first array, then use matching index in second array to pull up the value for that key.

I'm sorry, I can't replicate error (only few devices and not mine).

Now I don't see errors because I've added in both cases (webReq/storage)

- instanceof

- checking the size of array/dictionary

- looking for keys

Not to be pedantic, but I assume var d = {0 => "t"), x; contains a typo and should be var d = {0 => "t"}, x;.

It looks to me that this is not a case where d[1] and d.get(1) are not equivalent, but that you're receiving arrays in those two cases you mention. That makes sense to me since you'll see Array Out of Bounds when attempting d[1] and Symbol Not Found with d.get(1) if it is, in fact, an array. Just as an example, here's a quick check I did:

var d = {0 => "t"}, e = [1], x, y;

x = d[1];       // null
y = d.get(1);   // null

x = e[1];       // Array Out of Bounds error
y = e.get(1);   // Symbol Not Found error

These represent expected behaviors for Dictionaries (which will return null if the requested key does not exist) and Arrays, respectively.

We'll have to do some more in-depth investigation to see if we can reproduce when dealing with storage or converting from JSON. I am curious how exactly you're handling the JSON response, so if you have any code snippet you can share that demonstrates how you have this implemented, I'd appreciate it.

and you can see using [] is allowed to dictionary

Exception: UnexpectedTypeException: Expected Object/Array/Dictionary/ByteArray, given String

d[key] should be equivalent to d.get(key), if not, it should be forbidden

string has probably also associative array of chars but