💄 Avoid warning

Author: VincentLanglet

TwigCS/src/Token/Tokenizer.php

@@ -704,7 +704,7 @@ protected function lexPunctuation(): void
                 do {
                     array_pop($this->bracketsAndTernary);
                     $lastBracket = end($this->bracketsAndTernary);
-                } while ('?' === $lastBracket[0]);
+                } while (false !== $lastBracket && '?' === $lastBracket[0]);
 
                 // This is maybe the end of the variable, start again.
                 $this->lexVariable();