Compilation breaks in Swift 5.1 Ubuntu 16.04

What did you do?

Build a program that uses SwiftyJSON 5.0.0 as a dependency on Ubuntu 16.04

What did you expect to happen?

Compile cleanly

What actually happened instead?

Compilation failed:

.build/checkouts/SwiftyJSON/Source/SwiftyJSON/SwiftyJSON.swift:1215:51: error: ambiguous use of operator '<'
    case (.number, .number): return lhs.rawNumber < rhs.rawNumber
                                                  ^
.build/checkouts/SwiftyJSON/Source/SwiftyJSON/SwiftyJSON.swift:1251:6: note: found this candidate
func < (lhs: NSNumber, rhs: NSNumber) -> Bool {
     ^
Foundation.NSNumber:2:24: note: found this candidate
    public static func < (lhs: NSNumber, rhs: NSNumber) -> Bool
                       ^

Environment

List the software versions you're using:

• SwiftyJSON: 5.0.0
• Linux Version: Ubuntu 16.04.6 LTS
• Swift Version: Swift version 5.1 (swift-5.1-RELEASE) Target: x86_64-unknown-linux-gnu

Please also mention which package manager you used and its version. Delete the
other package managers in this list:

• Swift Package Manager: Swift Package Manager - Swift 5.1.0 (790a0c9)

Start with .build/checkouts/SwiftyJSON/Source/SwiftyJSON/SwiftyJSON.swift around lines 1215 and 1251, then reproduce the Swift 5.1 build on Ubuntu 16.04 using Swift Package Manager. Done means the reported comparison compiles cleanly without breaking the existing SwiftyJSON test suite.