PHP 8.5 | Tokenizer/PHP: fix "Using null as an array offset" deprecation

If a comment is on its own line, the new line token is merged into the comment token, and the new line is skipped by setting it to `null`.

Where the next line contains incomplete, or invalid, code which ends in an nullsafe operator (for example `$obj?`), the tokenizer will step backwards until it finds the next non-empty line.
The skipped new line token should be skipped during this parsing.
This can only occur during live coding or when a file has a parse error, but PHPCS should handle that situation gracefully.

Fixed now.

Fixes #1216.

This change is already covered via the existing tests.

Ref: https://wiki.php.net/rfc/deprecations_php_8_5#deprecate_using_values_null_as_an_array_offset_and_when_calling_array_key_exists

Author: andrewnicols

src/Tokenizers/PHP.php

@@ -2255,6 +2255,9 @@ protected function tokenize($string)
                 for ($i = ($stackPtr - 1); $i >= 0; $i--) {
                     if (is_array($tokens[$i]) === true) {
                         $tokenType = $tokens[$i][0];
+                    } else if ($tokens[$i] === null) {
+                        // Ignore skipped tokens.
+                        continue;
                     } else {
                         $tokenType = $tokens[$i];
                     }