Merge pull request #61 from aprat84/bugfix/check-string-offset-exists

Improve footer refs match

Author: marcocesarato

src/Git/Commit/Footer.php

@@ -49,9 +49,9 @@ public function __construct(string $token, string $value)
 
         $refs = [];
         $tokenLower = strtolower($this->token);
-        $values = preg_split('/[,\s]/', $this->value);
+        $values = preg_split('/[,\s]+/', $this->value, -1, PREG_SPLIT_NO_EMPTY);
         foreach ($values as $val) {
-            if ($val[0] === '#') {
+            if (isset($val[0]) && $val[0] === '#') {
                 $ref = ltrim($val, '#');
                 $obj = new Reference($ref);
                 if (in_array($tokenLower, self::TOKEN_CLOSE_ISSUE)) {