Array indexing check false positive with explicit isset

[quasilyte]

Since getting a non-existing element in KPHP leads to different results ("empty value of array type element" instead of null), people sometimes tend to write code like this:

$v = isset($data['k']) ? $data['k'] : '';
if ($v !== '') { // <- warning here
}

It makes sure that for both KPHP and PHP this code could behave identically.

But it looks like KPHP does not recognize this idiom.

Do we have any hints for this case (for example, !empty($v), etc.)?
In that case, we could suggest a potential fix to the problem inside the warning message.

Is it practical to improve this particular diagnostic so it doesn't report such cases?