When I have a timediff() on a field that returns null I get an java.lang.NullPointerException error. I found a way to solve it by just adding a contact( timediff () , ‘’) and adding a whitespace will fix the error.
The second issue is related -I would guess - when exploring a table that has a column time and the column has null fields, I am unable to explore it. The visualisation fails with the same error java.lang.NullPointerException
I am using MySQL 8 and latests version of metabase.