Stringy Error

String+Error.swift

extension Optional {

    public func or(throw error: @autoclosure () -> Error) throws -> Wrapped {
        guard let wrapped = self else { throw error() }
        return wrapped
    }
}

extension String {
    
    public func error(
        _ function: String = #function,
        _ file: String = #file,
        _ line: Int = #line
    ) -> Error {
        .init(message: self, function: function, file: file, line: line)
    }
    
    public struct Error: Swift.Error, CustomStringConvertible, CustomDebugStringConvertible {
        
        let message: String
        let function: String
        let file: String
        let line: Int
        
        public var description: String { message }
        public var debugDescription: String { "\(message) ← \(file)#\(line)" }
    }
}

extension Error {
    public var message: String { description }
}

try dictionary[key.stringValue].or(throw: "No value found for key '\(key.stringValue)'".error())