UITableViewCell height problems

As you will guess from what you are about to read I am extremely new at swift and IOS coding. I'm trying to display content on a UITableview using a UITableViewController and a custom coded UITableViewCell. In this cell I have two items, an imageview and a label. Both get populated with their corresponding data programmatically. The problem that I am having is laying out the image and the label inside the customcell class the way that I want. More specifically, I'm having problems figuring out what is driving the height of the custom cell's row when the project runs. Ideally I'd like the imageview to set this height constraint (along with the width), regardless of the size of the original image asset. But when I set the imageview's height constraints I get an error in the debugger telling me that it is "Unable to simultaneously satisfy constraints" and it mentions the constraints that I have set for the imageview's bottom & height in the error code accordingly. This is as close as I have been able to run the project to make it look like I want but I keep getting that error.

I read somewhere that in order to have autolayout work properly in code I have to set the imageview's leading, top and bottom constraints somehow. But if I do not set a height constraint for the imageview then the table view uses the original height for the image and throws off the look of the table. These are the snippets of code that I have that I think are relevant:

code inside my TableviewController "viewDidLoad()" function

self.tableView.rowHeight = UITableView.automaticDimension
self.tableView.estimatedRowHeight = 200

code inside the custom "UITableViewCell" class declaration

    var messageLabel: UILabel = {
        var label = UILabel()
        label.translatesAutoresizingMaskIntoConstraints = false
        label.backgroundColor = .blue  // REMOVE ME JUST FOR TESTING
        label.textColor = .black
        label.font = UIFont(name: "Verdana", size: 20)
        return label
    }()

    var mainImageView: UIImageView = {
        var imageView = UIImageView()
        imageView.contentMode = .center // image will never be stretched veritically or horizontally
        imageView.clipsToBounds = true
        imageView.translatesAutoresizingMaskIntoConstraints = false //enable auto layout
        imageView.layer.cornerRadius = imageView.frame.size.width / 2
        imageView.backgroundColor = .red  // REMOVE ME JUST FOR TESTING
        return imageView
    }()

code inside the "override init(style:UITableViewCell.CellStyle, reuseIdentifier: String?)" function

        super.init(style: style, reuseIdentifier: reuseIdentifier)
    
        //add the views that we have created to this cell
        self.contentView.addSubview(mainImageView)
        self.contentView.addSubview(messageLabel)

        //add constraints for each of the views
        mainImageView.topAnchor.constraint(equalTo: self.contentView.topAnchor).isActive = true
        mainImageView.leadingAnchor.constraint(equalTo: self.contentView.leadingAnchor).isActive = true
        mainImageView.bottomAnchor.constraint(equalTo: self.contentView.bottomAnchor).isActive = true //dynamic row height also requires bottom constraints
        mainImageView.widthAnchor.constraint(equalToConstant: 100).isActive = true
      
        messageLabel.topAnchor.constraint(equalTo: self.contentView.topAnchor).isActive = true
        messageLabel.leadingAnchor.constraint(equalTo: mainImageView.trailingAnchor, constant: 5).isActive = true
        messageLabel.bottomAnchor.constraint(equalTo: self.contentView.bottomAnchor).isActive = true

One of the things that I tried was to test the results by commenting out the "mainImageView" bottom constraint and just specify a height constraint for the imageview. But the result was that the images overlapped on top of each other and the text labels' heights did not match the images.

I don't know what I am missing. What am I doing wrong or not doing?

Thanks.