Fix unit conversion after reduction

[SouthEndMusic]

Issue addressed

Fixes #974

Explanation

Some reducers created Generator objects instead of a Float64 or Vector{Float64}, which then dispatched to the fallback method of from_SI as @JoostBuitink mentioned.

@JoostBuitink regarding the testing you mentioned: can you make an issue with an overview of what should be tested and ideally also which test models can be used for it? See also #864.

[JoostBuitink]

This did not fix the issue, as the function is still dispatching on

Wflow.jl/Wflow/src/units.jl

Line 313 in af8225f

from_SI(x, unit::Unit; kwargs...) = x

This is because of the following:

typeof(reducer_(vector)) = Vector{Float64} 

while from_SI expects an AbstractFloat.

I'll create a separate issue to describe how to add this functionality to the tests

[SouthEndMusic]

I added an AbstractArray method for from_SI, based on your comment that should fix it

[JoostBuitink]

Thanks that did indeed solve this!