I got this error. It appears in my case that an array I was using to populate views with a ForEach loop increased in size over time and began to include duplicates. When I removed the duplicates from the array, these errors stopped.

If you simplify the let gradient line to let gradient = Gradient(colors: [.red, .green, .blue]) It works

I had the same problem. Then I let Google Chrome fill in my number which was prefixed with +44 and ASC accepted it.