fixed type error on breakdown filter

[EDsCODE]

Addresses #759

Changes

• fixed numeric breakdown values not working

Checklist

• All querysets/queries filter by Team (if applicable)
• Backend tests (if applicable)

[EDsCODE]

@timgl This should solve the issue but I found something funny that we should address. When you breakdown by a property, are the leftovers (anything that doesn't have the property) supposed to be displayed?

Right now, if you breakdown by browser_version it will give you the line with the browser version but also a line with 'nan'. Also, when clicking on the points of the 'nan' line even if the datapoint is 0, a list of users will be query-able.

[timgl]

i don't have a strong opinion either way. I think it can be useful to have the non-set line too so if it's easy to make it work.

Re the 0 being clickable, it just shows '0 users found' so I think that's fine. I did find a bug where setting properties on entities doesn't correctly filter /people, will create a ticket for that

[EDsCODE]

Fixed! The 0 person error was happening on numerical breakdowns also. So I was seeing a line with 0 but when you clicked on a datapoint you'd see actual people related to the event. The problem was that when something was nan we were tossing the results rather than aggregating them. I changed it so that it treats nan and nones as strings and become a breakdown category which will be displayed as "other" in the label