unity-reviewer

Unity Code Reviewer

Run through these checks after modifying or creating C# scripts. Organized by severity.

Critical (Will Break at Runtime)

CHECK: Missing Event Unsubscription

Wrong (common default):

void OnEnable() {
    GameEvents.OnPlayerDied += HandlePlayerDied;
}
// No OnDisable — listener persists after destroy, causes NullReferenceException

Right:

void OnEnable() {
    GameEvents.OnPlayerDied += HandlePlayerDied;
}
void OnDisable() {
    GameEvents.OnPlayerDied -= HandlePlayerDied;
}

Why it matters: Leaked subscriptions cause NullReferenceExceptions when the destroyed object's method is called. One of the most common Unity bugs.

CHECK: Unity Fake Null

Wrong (common default):

var go = GetComponent<SomeComponent>();
var result = go?.DoThing(); // C# null check — DOES NOT catch Unity destroyed objects

Right:

var go = GetComponent<SomeComponent>();
if (go != null) go.DoThing(); // Unity's == override catches destroyed objects

Why it matters: Unity overrides == to return true for destroyed objects, but C#'s ?. and ?? bypass this override. Object appears non-null to C# but is actually destroyed.

CHECK: Accessing Unity API from Background Thread

Wrong:

async Task LoadDataAsync() {
    var data = await FetchFromServer();
    transform.position = data.position; // CRASH: not on main thread
}

Right:

async Task LoadDataAsync() {
    var data = await FetchFromServer();
    await Awaitable.MainThreadAsync(); // Switch back to main thread
    transform.position = data.position;
}

Why it matters: Unity API is not thread-safe. Accessing transforms, GameObjects, or components from a background thread causes crashes or silent corruption.

CHECK: Destroy vs DestroyImmediate

Wrong:

void CleanUp() {
    DestroyImmediate(gameObject); // Dangerous outside editor scripts
}

Right:

void CleanUp() {
    Destroy(gameObject); // Deferred to end of frame, safe
}