Simplify PhpFileParser::getExtraTypes() logic (#25)

The first time the method is called, a string is built up with `|`-separated
extra types, then split based on `|`s, the resulting array is filtered to
exclude non-empty strings, and that array is finally passed to
`PhpFileCleaner::setTypeConfig()`. Given that the array only has at most a
single entry, just set the array directly.

Author: DanielEScherzer

src/PhpFileParser.php

@@ -125,13 +125,12 @@ private static function getExtraTypes(): string
 
         if (null === $extraTypes) {
             $extraTypes = '';
+            $extraTypesArray = [];
             if (PHP_VERSION_ID >= 80100 || (defined('HHVM_VERSION') && version_compare(HHVM_VERSION, '3.3', '>='))) {
                 $extraTypes .= '|enum';
+                $extraTypesArray = ['enum'];
             }
 
-            $extraTypesArray = array_filter(explode('|', $extraTypes), function (string $type): bool {
-                return $type !== '';
-            });
             PhpFileCleaner::setTypeConfig(array_merge(['class', 'interface', 'trait'], $extraTypesArray));
         }