What is the common 'Steam Cloud Error' for Stardew Valley on macOS, and how does it manifest?

The 'Steam Cloud Error' for Stardew Valley on macOS typically indicates an issue with Steam's ability to synchronize your local save files with the cloud servers. This can manifest in several ways: the game might fail to launch, display a 'Cloud Sync Conflict' message upon startup, or even seem to lose your progress if local and cloud saves diverge or a sync fails. It often occurs when the game is not properly closed, an internet connection is unstable during sync, or if there's a discrepancy between the local save file version and the one stored in the cloud.