MAINT: handle single detection case in `Diffusion`
MAINT: handle single detection case in `Diffusion`

guillochon/MOSFiT,guillochon/MOSFiT,bmockler/MOSFiT,villrv/MOSFiT,mnicholl/MOSFiT,guillochon/MOSFiT,mnicholl/MOSFiT,villrv/MOSFiT,bmockler/MOSFiT,mnicholl/MOSFiT,guillochon/FriendlyFit