PHP 8.5 | File::getMemberProperties(): fix "Using null as an array offset" deprecation

If a variable in the global scope is passed to `File::getMemberProperties()`, the token may not have any "conditions".
This would result in `array_keys()` returning an empty array, which will cause `array_pop()` to return `null`, leading to the deprecation notice.

Fixed now via some extra defensive coding.

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: jrfnl

src/Files/File.php

@@ -1876,6 +1876,10 @@ public function getMemberProperties($stackPtr)
             throw new RuntimeException('$stackPtr must be of type T_VARIABLE');
         }
 
+        if (empty($this->tokens[$stackPtr]['conditions']) === true) {
+            throw new RuntimeException('$stackPtr is not a class member var');
+        }
+
         $conditions = array_keys($this->tokens[$stackPtr]['conditions']);
         $ptr        = array_pop($conditions);
         if (isset($this->tokens[$ptr]) === false