Small fixes

- Remove redundant type cast
- Fix Qnil to 0 as a member of rb_parser_ary_t is not a VALUE
- Delete unused line

node.c

@@ -188,7 +188,7 @@ static void
 parser_ast_token_free(rb_ast_t *ast, rb_parser_ast_token_t *token)
 {
     if (!token) return;
-    parser_string_free(ast, (rb_parser_string_t *)token->str);
+    parser_string_free(ast, token->str);
     xfree(token);
 }
 
@@ -259,8 +259,6 @@ free_ast_value(rb_ast_t *ast, void *ctx, NODE *node)
 static void
 ast_tokens_free(rb_ast_t *ast)
 {
-    rb_parser_ary_t *tokens;
-
     if (!ast || !ast->node_buffer) return;
     parser_ary_free(ast, ast->node_buffer->tokens);
 }

parse.y

@@ -2600,7 +2600,7 @@ rb_parser_ary_extend(rb_parser_t *p, rb_parser_ary_t *ary, long len)
             ary->data = xrealloc(ary->data, sizeof(void *) * len);
         }
         for (i = ary->len; i < len; i++) {
-            ary->data[i] = Qnil;
+            ary->data[i] = 0;
         }
     }
 }
@@ -2622,7 +2622,7 @@ rb_parser_ary_new_capa(rb_parser_t *p, long len)
         ary->data = NULL;
     }
     for (i = 0; i < len; i++) {
-        ary->data[i] = Qnil;
+        ary->data[i] = 0;
     }
     return ary;
 }