Aggregations functions return type

[natocTo]

• bug report? yes
• feature request? no
• version: 3.0.0-alpha

Description

Selection aggregations function have return type int but should be able to return null or int.

Steps To Reproduce

max() min() on empty table atc.

[adaamz]

Or I can call aggregation on string column.
$selection->min('myStringColumn')

[dg]

Can you send PR?

[natocTo]

Actually I am not sure what is right if it also works with strings atc. Remove return type completely?