issue a warning or error on constructing Axis with duplicate symbols

[bgctw]

Currently, constructing an Axis from a Tuple of symbols silently ignores duplicate symbols and only records position of the last occurrence:

julia> Axis((:a,:a))
Axis(a = 2,)

What is the reason for this behavior?

My use case is attaching positions to an existing Vector: ComponentVector([1,2],Axis((:a,:a)))
I would expect at least a warning here.

[jonniedie]

Thanks for the issue! Fixed in v0.11.17