How to Fix a Pygame Level Load KeyError From Missing JSON Fields

Loading a level crashes with KeyError: 'speed' because one level file omits that field. Bracket access assumes every key exists. Use .get with defaults and validate required keys explicitly.

How to fix it

1. Use get with defaults

Read optional fields with data.get('speed', 1.0) so a missing key yields a sensible default instead of raising KeyError.

2. Validate required keys

For fields that truly must exist, check for them up front and raise a clear, named error identifying the file and key, rather than failing deep in the code.

3. Guard the load

Wrap the per-file load in try/except so a malformed or incomplete file logs an error and is skipped, keeping the rest of the content loadable.

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 Pygame 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.