Shortcode Core v5.2.0 causes SimpleSearch to crash

Hi!

After updating to **Shortcode Core v5.2.0**, **SimpleSearch Plugin** stopped working.

```
RuntimeException
PCRE failure `4`.

/user/plugins/shortcode-core/vendor/thunderer/shortcode/src/Parser/RegularParser.php

...
private function tokenize($text)
{
$count = preg_match_all($this->lexerRegex, $text, $matches, PREG_SET_ORDER | PREG_OFFSET_CAPTURE);
if(false === $count || preg_last_error() !== PREG_NO_ERROR) {
throw new \RuntimeException(sprintf('PCRE failure `%s`.', preg_last_error()));
}
...
```

Specifically this line:

```
throw new \RuntimeException(sprintf('PCRE failure `%s`.', preg_last_error()));
```