Avoid nil icon color in watch config (#3073)

<!-- Thank you for submitting a Pull Request and helping to improve Home
Assistant. Please complete the following sections to help the processing
and review of your changes. Please do not delete anything from this
template. -->

## Summary
<!-- Provide a brief summary of the changes you have made and most
importantly what they aim to achieve -->

## Screenshots
<!-- If this is a user-facing change not in the frontend, please include
screenshots in light and dark mode. -->

## Link to pull request in Documentation repository
<!-- Pull requests that add, change or remove functionality must have a
corresponding pull request in the Companion App Documentation repository
(https://github.com/home-assistant/companion.home-assistant). Please add
the number of this pull request after the "#" -->
Documentation: home-assistant/companion.home-assistant#

## Any other notes
<!-- If there is any other information of note, like if this Pull
Request is part of a bigger change, please include it here. -->

Sources/App/Settings/MagicItem/Edit/MagicItemCustomizationView.swift

@@ -51,7 +51,13 @@ struct MagicItemCustomizationView: View {
 
                 Section {
                     ColorPicker(L10n.MagicItem.IconColor.title, selection: .init(get: {
-                        Color(hex: viewModel.item.customization?.iconColor)
+                        var color = Color(uiColor: Asset.Colors.haPrimary.color)
+                        if let configIconColor = viewModel.item.customization?.iconColor {
+                            color = Color(hex: configIconColor)
+                        } else {
+                            viewModel.item.customization?.iconColor = color.hex()
+                        }
+                        return color
                     }, set: { newColor in
                         viewModel.item.customization?.iconColor = newColor.hex()
                     }), supportsOpacity: false)