Severity: Warning -- Undefined array key «id»

Severity: Warning --> Undefined array key "id"

You are using an undefined array key, that is, a key that does not exist. To prevent this warning from being issued, you can add checks:

• if (isset($array['id'])) { // Your code }

• $array['id'] = $array['id'] ?? ""; // php7+ Null concatenation operator 
  // This is identical to the following code:
  $array['id'] = ! empty(array['id']) ? array['id'] : "";
  

It's important to note that isset() only checks for the existence of a variable, while empty() checks for presence and emptiness.

if ( ! empty($array['id'])) { // Your code }
// This is similar to the following code:
if ( isset($array['id']) && $array['id']) { // Your code }