Improve handling argument types in ReservedWordsCommand

lib/Doctrine/DBAL/Tools/Console/Command/ReservedWordsCommand.php

@@ -33,6 +33,7 @@ use function array_keys;
 use function assert;
 use function count;
 use function implode;
+use function is_array;
 use function is_string;
 use function trigger_error;
 
@@ -149,7 +150,14 @@ EOT
     {
         $conn = $this->getConnection($input);
 
-        $keywordLists = (array) $input->getOption('list');
+        $keywordLists = $input->getOption('list');
+
+        if (is_string($keywordLists)) {
+            $keywordLists = [$keywordLists];
+        } elseif (! is_array($keywordLists)) {
+            $keywordLists = [];
+        }
+
         if (! $keywordLists) {
             $keywordLists = [
                 'mysql',