minor #4546 DX: removing unnecessary variable initialization (kubawerlos)

This PR was merged into the 2.15 branch.

Discussion
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DX: removing unnecessary variable initialization

Spotted when working on kubawerlos/php-cs-fixer-custom-fixers#132

Both variables will be initialized in `if` and in `else`.

Commits
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bbd94b0 DX: removing unnecessary variable initialization

Author: SpacePossum

src/Fixer/PhpUnit/PhpUnitTestClassRequiresCoversFixer.php

@@ -88,8 +88,6 @@ private function addRequiresCover(Tokens $tokens, $startIndex)
             : '';
 
         $prevIndex = $tokens->getPrevNonWhitespace($index);
-        $doc = null;
-        $docIndex = null;
 
         if ($tokens[$prevIndex]->isGivenKind(T_DOC_COMMENT)) {
             $docIndex = $prevIndex;