magento 2 Deepest Category product list page gives Error 500. Which files to inspect?

Question

The site I'm working on the lowest category page (suppose to be list view) give the error 500.
I'm not quite remember file I edited.
search result also return the same error. Which files should I look into to fix the error?

Thanks.

this is the error from debug.log [2019-02-22 06:36:35] main.DEBUG: cache_invalidate: {"method":"GET","url":"https://dev.siig.com/it-products/video-display/display-adapters/usb-2-0.html","invalidateInfo":{"tags":["interception","CONFIG"],"mode":"matchingTag"}} [] [2019-02-22 06:37:41] main.DEBUG: cache_invalidate: {"method":"GET","url":"http:/","invalidateInfo":{"tags":["interception","CONFIG"],"mode":"matchingTag"}} []

Answer 1

finally found the file that was causing the issue. it was the app/design/frontend/Infortis/base/Magento_LayeredNavigation/templates/layer/view.phtml that was containing some bad codes...