Also experiencing this since I updated to Sequoia 15.2, and finally identified the conditions under which this happens, as well as a workaround:
If you drag and drop a song in a playlist, and that playlist is set to view "as Playlist" in the "View" settings, and the song you try to drag does not have an album title, then Apple Music main thread crashes with a swift::swift_dynamicCastFailure.
If you try to drag the same song with the "View" set to "as Songs", or any other view besides "as Playlist", then there is no crash.
If you edit the metadata of the song to have an album title, and then allow the playlist UI to refresh by clicking on the playlist in the sidebar again, and then attempt to drag the song, then the app will not crash.
In contrast, if you edit a song without an album title to have an album title, save, but do not allow the playlist UI to refresh (so that the UI is still not showing an album title), and then try drag the song, the app will crash.
This is reproducible every time.
This is a SwiftUI bug and has nothing to do with the specific of the song, or even the underlying metadata. The temporary workaround is to view your playlists "as Songs".
OS: macOS 15.2 (24C101)
Apple Music: 1.5.2