fix: add safety checks to prevent runtime crashes

[Tusharjamdade]

Changes

This PR adds defensive checks to prevent the application from crashing in multiple edge cases, including:

• Connecting a funnel (event source) directly to a sink.
• Attempting invalid connections after a valid Trigger → Sink path is already established.
• Starting the simulation with incomplete or partially configured event paths.
• Handling cases where conveyor and destination states become out of sync.
• Preventing runtime errors caused by null references, deleted event nodes, or out-of-bounds access.

The gameplay and learning flow remain unchanged the system now handles invalid user interactions gracefully instead of crashing.

/kind

Fixes #62

Release Note
Fixed a crash that could occur when users created invalid or incomplete event flow connections. The game now handles such interactions gracefully across all levels.

Docs

[knative-prow]

@Tusharjamdade: The label(s) kind/<kind> cannot be applied, because the repository doesn't have them.

Details

In response to this:

Changes

This PR adds defensive checks to prevent the application from crashing in multiple edge cases, including:

• Connecting a funnel (event source) directly to a sink.
• Attempting invalid connections after a valid Trigger → Sink path is already established.
• Starting the simulation with incomplete or partially configured event paths.
• Handling cases where conveyor and destination states become out of sync.
• Preventing runtime errors caused by null references, deleted event nodes, or out-of-bounds access.

The gameplay and learning flow remain unchanged the system now handles invalid user interactions gracefully instead of crashing.

/kind

Fixes #62

Release Note
Fixed a crash that could occur when users created invalid or incomplete event flow connections. The game now handles such interactions gracefully across all levels.

Docs

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[knative-prow]

[APPROVALNOTIFIER] This PR is NOT APPROVED

This pull-request has been approved by: Tusharjamdade
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[linux-foundation-easycla]

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• ✅ login: Tusharjamdade / name: Tushar Jamdade (ce504b5)

[knative-prow]

Welcome @Tusharjamdade! It looks like this is your first PR to knative-extensions/educational-game 🎉

[Tusharjamdade]

Hi @Cali0707, @ankitajana21 and @prajjwalyd,

Could you please take a look and let me know if there are any required changes?
I would also recommend watching the videos linked in the issue description to understand how the system crashes.

Fix:

2026-01-28.22-46-32.mp4

This PR resolves one of the issues demonstrated in the video.

[knative-prow-robot]

PR needs rebase.

Details

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