I'm running into some issues creating an array out of other arrays and slices of other arrays. All arrays referenced here are internal static let [UInt16] declared earlier. They are all contained in the same struct.
internal static let bigarray = [UInt16]([0, array1, array2, array3, array4, array5, [UInt16](array6.prefix(upTo: array6.count-8))].joined())
The error message is misleading. The real problem is that
the first element
0 in the "array of arrays"
[0, array1, array2, ... ]
is not an array, but a number. Changing that to
 should solve the problem. Note that the expression can be simplified slightly to
let bigarray = [, array1, array2, array3, array4, array5, Array(array6.dropLast(8))].joined()