Module productscategory and FullPageCache

[Quant]

The productscategory module gives errors if you enable FullPageCache and disable caching for displayFooterProduct.

[Mon Apr 22 18:26:22.209248 2019] [:error] [pid 25072] [client 127.0.0.1:53663] PHP Notice:  Undefined index: product in /home/shop/www/modules/productscategory/productscategory.php on line 110, referer: http://tb.local/19-laki
[Mon Apr 22 18:26:22.209278 2019] [:error] [pid 25072] [client 127.0.0.1:53663] PHP Notice:  Trying to get property of non-object in /home/shop/www/modules/productscategory/productscategory.php on line 110, referer: http://tb.local/19-laki
[Mon Apr 22 18:26:22.209294 2019] [:error] [pid 25072] [client 127.0.0.1:53663] PHP Notice:  Undefined index: product in /home/shop/www/modules/productscategory/productscategory.php on line 111, referer: http://tb.local/19-laki
[Mon Apr 22 18:26:22.209698 2019] [:error] [pid 25072] [client 127.0.0.1:53663] PHP Notice:  Trying to get property of non-object in /home/shop/www/modules/productscategory/productscategory.php on line 113, referer: http://tb.local/19-laki

Im use TB ver 1.0.8 (community theme) and php5.6.

How to fix it?

[wakabayashi]

I think, you shouldn't use FullPageCache for now.

Btw: is there are reason for just using 5.6?

[Quant]

The problem disappears if you update the TB via CoreUpdater. Then the errors disappear.
Ps. I use php5.6, only for the test, while I transfer PS1.6.1.23 to TB.