Symfony version(s) affected

5.4.30

Description

symfony/http-foundation@2213955

Create many warnings on php 7.2 and not identical work on php 7.2\8.1

• Uninitialized string offset: 0
  /HeaderUtils.php(266)

• $separators on 7.2 possible false

How to reproduce

run on php 7.2-7.4

Possible Solution

    private static function groupParts(array $matches, string $separators, bool $first = true): array
    {
        $separator = $separators[0];
        $separators = substr($separators, 1) ?: '';

Additional Context

No response