SwiftUI Preview: Updating took more than 5 seconds for non-main target (framework target)

While selecting a framework rather than the executable as the active scheme,
SwiftUI preview cannot use: Updating took more than 5 seconds.

However, while selecting the main app target, it can work perfectly.

Repro steps:

1. git clone https://github.com/imWildCat/NonExecutableTargetCannotUseSwiftUIPreviewDemo

2. cd NonExecutableTargetCannotUseSwiftUIPreviewDemo

3. xed NonExecutableTargetCannotUseSwiftUIPreviewDemo.xcworkspace

4. Select the “SharedUI” target as the active scheme

5. Open the WebImage.swift source file

6. Run the SwiftUI preview

Please note that, if you use the main app target (executable rather than the frame), it can be previewed.