Issue Description:

let foo: [String: Int] = "foo; foo; bar; bar; bar bar; foo foo"
.components(separatedBy: "; ")
.reduce(into: [String: Int]()) { 
    $0[$1] = $0[$1] == nil ? 1 : $0[$1]! += 1 
}

Hey. I want with a minimal amount of code, actively using syntactic sugar and in one call chain to calculate the frequency of repeating lines in the source line.
With the ternary operator this approach does not work, the compiler swears: "Cannot subscript a value of incorrect or ambiguous type".

But using the usual "if let" statement everything works in a distorted way.
Tell me, where did I make a mistake?