NA plot shows up when show forecasts checkbox checked with certain forecasters selected

[kateharwood]

1. Choose an "as of" date
2. Select "Show Forecasters' Predictions"
   One example:
3. Select forecaster imperial-ensemble2
4. Select location AK

[nmdefries]

More specifically, this bug is triggered when moving from a location selection where one of the selected forecasters has no data to another location where that forecaster has no data, and the destination location is a state.

For example, imperial-ensemble2 is available for the US only. Moving from "US" with imperial-ensemble2 and at least one other forecaster selected to "AK" (imperial-ensemble2 not available) does not trigger the bug. Moving from "AK" to "AL", however, does. Moving from "AK" to "Totaled Over States" does not.

"Show forecaster predictions" selection is not necessary to replicate this bug, but a past as-of date is necessary.

Switching the as-of date from the most recent to a past date while imperial-ensemble2 and at least one other forecaster are selected and location is "AK" (imperial-ensemble2 not available) does not trigger the bug until selecting another location where imperial-ensemble2 is not available or "show forecaster predictions" is toggled on.