The current logic is expecting the exposed type filter to always be an array. This causes
csv exports to break when exporting from the all quantities page because the quantity
type filter does not allow multiple values. When no quantity type is provided the type
filter is set to 'All'.
**Why?** Make it possible for novice users to find data and explore connections
between assets/logs without needing to totally grok the farmOS data model first.
i.e.
* Navigate from a plant asset to a list of all the seed/plant assets with the same crop/variety
* Navigate from a plant asset to a list of all the seed/plant assets from the same season
* Navigate from a log in the compost category to a list of all the logs in the compost category
* Navigate from a material asset to a list of all the materials with the same material type