Quick answer: Serialize from a single authoritative game-state model at a safe point, or defer the save until the current action fully resolves.
Saving while a move is still resolving can capture half-applied state that crashes on load. Snapshotting at a safe boundary fixes it. Here is how.
How to fix it
1. Save from one model
Keep all game truth in a serializable state model separate from views and animations. Save that model so transient visual state never leaks into the save.
2. Defer to a safe boundary
If an action is mid-resolution, queue the save request and execute it once the action fully commits and pending effects have applied, so you never snapshot a partial state.
3. Validate on load
Version the save and validate invariants (counts, references resolve) on load. Reject or repair an inconsistent save instead of crashing partway through reconstruction.
Catching the ones you can't reproduce
The hardest version of this to fix is the one you can't reproduce — it only happens on a player's hardware, OS, driver, or save state, under conditions that simply aren't present on your machine. A report that says “it crashed” or “it froze” gives you nothing to act on, so the bug survives release after release while quietly costing you players.
Automatic error capture closes that gap. Each failure arrives with its full stack trace, the device and OS, the build number, and a breadcrumb trail of what the player did right before it broke, so even a failure you have never seen becomes a specific, reproducible issue. Fold identical failures into one signature ranked by how many players each hits, and your worklist sorts itself worst-first instead of arriving as a stream of vague complaints.
This is where a tool like Bugnet earns its place. Its SDK captures every Godot error automatically with the full stack trace plus device, OS, memory, build, and game-state context, folds duplicates into one grouped issue with an occurrence count, and ties each to the build it first appeared on — so you fix the problem that hurts the most players first and confirm it is gone when its signature disappears from the next release.
The bug you can't reproduce isn't gone — it's just invisible until you capture it from the player's device.