Please don't force unwrap <3

Thank you! :D

Getting an annoying error on Swift

main.swift:64:23: error: use of unresolved identifier 'Base64Chars'
                        returnChars[i*4] = Base64Chars[char1 >> 2]
                                           ^~~~~~~~~~~
main.swift:6:13: note: did you mean 'base64Chars'?
        static let base64Chars: [UInt8] = Array("ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/".utf8)
                   ^
                   ```