Commented out glass is certainly a problem (if it's not only a comment) as the instance of object is created elsewhere but there's some more problems in the code:

-Software tester removes the glass but the water still stands there in the shape of the glass.

-QA tries to pour the water in to the glass but water doesn't register and the glass doesn't fill.

-Performance testing notes that rendering the glass needs some optimization since the glass doesn't fill over 50% before being out of memory.

-Junior programmer can't get the glass to run since the liquids library wasn't locked down and got an incompatible update.

-Automation testing results in to a crash with a screenshot and logs that point out that glass frontend use the old version of the glass backend API leading the glass to freeze.

-External testing points out that there's a bug in the glass but they can't identify it.