Nil fontName leads to crash

[Rspoon3]

Running the basic example from the README causes a crash.

System Info:

• Xcode 13.3.1 (13E500a)
• iPad Pro 11 Inch 3rd Generation (iOS 15.4 Simulator)

Reproduction steps:

1. Create a new Xcode project
2. Add FontAwesome via Swift Package Manager
3. Copy and paste the code below
4. Run the application

import UIKit
import FontAwesome

class ViewController: UIViewController {
    let imageView = UIImageView()

    override func viewDidLoad() {
        super.viewDidLoad()

        imageView.translatesAutoresizingMaskIntoConstraints = false
        imageView.image = UIImage.fontAwesomeIcon(name: .github,
                                                  style: .regular,
                                                  textColor: .systemPurple,
                                                  size: .init(width: 300, height: 300))

        view.addSubview(imageView)

        NSLayoutConstraint.activate([
            imageView.centerXAnchor.constraint(equalTo: view.centerXAnchor),
            imageView.centerYAnchor.constraint(equalTo: view.centerYAnchor),
            imageView.widthAnchor.constraint(equalToConstant: 400),
            imageView.heightAnchor.constraint(equalToConstant: 400),
        ])
    }
}

Actual Results: A crash occurs due to the fontName being nil

Expected Results: An image should render

[Rspoon3]

Duplicate of https://github.com/thii/FontAwesome.swift/issues/236