fix: Check "other" is mounted before accessing parent

[gnarhard]

Status

READY

Description

After some recent Flame engine updates, hot-swapping component hitboxes threw an error trying to find the parent of the "other" entity collision. This checks that the "other" component is mounted before continuing to find the entity.

Type of Change

• ✨ New feature (non-breaking change which adds functionality)
• 🛠️ Bug fix (non-breaking change which fixes an issue)
• ❌ Breaking change (fix or feature that would cause existing functionality to change)
• 🧹 Code refactor
• ✅ Build configuration change
• 📝 Documentation
• 🗑️ Chore

Summary by CodeRabbit

• Bug Fixes
  • Improved stability by preventing potential errors during collision detection when components are not properly mounted.

[coderabbitai]

Walkthrough

A method in the PropagatingCollisionBehavior class was updated to check if a component is mounted before proceeding. The method now safely accesses the parent of a behavior using a null-aware operator, reducing the risk of runtime exceptions from unmounted or null components.

Changes

File Path	Change Summary
packages/flame_behaviors/lib/src/behaviors/propagating_collision_behavior.dart	Updated _findEntity to check if other is mounted and use null-aware access for parent lookup

Poem

In the garden of code, where collisions abound,
A check for “isMounted” now safely is found.
No more surprise crashes, just smooth bunny hops,
With null-aware steps, the exception count drops.
Hooray for safe parents and behaviors refined—
The code’s running smoothly, with bugs left behind! 🐇✨

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📥 Commits

Reviewing files that changed from the base of the PR and between 6772c9f and f7461cd.

📒 Files selected for processing (1)

• packages/flame_behaviors/lib/src/behaviors/propagating_collision_behavior.dart (2 hunks)

🔇 Additional comments (2)

packages/flame_behaviors/lib/src/behaviors/propagating_collision_behavior.dart (2)

108-112: Good defensive programming to check for mounted state.

Adding this check prevents potential errors when trying to access the parent of an unmounted component. This is an important safeguard in game development where components can be removed during gameplay.

---

122-122: Improved null-safety with nullable casting.

The change from forced casting to using a null-aware operator is a good defensive programming practice. This prevents potential runtime exceptions if the parent isn't a PropagatingCollisionBehavior or if it doesn't have a parent.

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[gnarhard]

@VGVentures can I get a merge, please?

[gnarhard]

@wolfenrain can you help me out here in getting this merged. Didn't you author this?

[alestiago]

Hi @gnarhard, I no longer have merge privileges but I'll share it with the team to see if you can get a review and merger.

[alestiago]

@gnarhard I've noticed we're missing some tests for it. Can you add some?

If you need help adding them don't hesitate to drop any question on this issue.

[alestiago]

After some recent Flame engine updates, hot-swapping component hitboxes threw an error trying to find the parent of the "other" entity collision. This checks that the "other" component is mounted before continuing to find the entity.

By any chance could you share a minimal reproductive sample that shows this behavior happening? It will facilitate reviewers gathering all the context about your fix.

[alestiago]

@gnarhard this seems to be a bit silent for a while, are you still able to push this forward? Can myself or the team help out in any form to push this forward?

[gnarhard]

Naw I'm just procrastinating

[gnarhard]

@alestiago I appreciate your patience with me on this. I added a test that handles the specific scenario this PR fixes: An entity is removed while collision(s) are still processing.

[gnarhard]

@erickzanardo @alestiago can we get a release with this, please?