Give a good error for duplicated fields

[Seelengrab]

It would be nice to be able to point at the exact fields that are duplicated, instead of just pointing out that they are.

FieldFlags.jl/src/FieldFlags.jl

Line 155 in 9d9591e

allunique(filter(!=(:_), fieldtuple)) || throw(ArgumentError("Fields need to be uniquely identifiable!"))

FieldFlags.jl/src/FieldFlags.jl

Line 514 in 9d9591e

allunique(filter(!=(:_), fields)) || throw(ArgumentError("Fields need to be uniquely identifiable!"))