fix(autofix): Handle missing state in get_autofix_state (#97556)

Fixes
[SENTRY-43FP](https://sentry.io/organizations/sentry/issues/6709226854/).
The issue was that: GitHub webhook for non-Autofix PR caused Seer to
return null state, leading to `DictError` during validation.

- Explicitly check for a missing `state` key in the result of
`get_autofix_state`.
- Return `None` if the `state` key is missing to avoid errors when
validating.


This fix was generated by Seer in Sentry, triggered by Rohan Agarwal. 👁️
Run ID: 734775

Not quite right? [Click here to continue debugging with
Seer.](https://sentry.io/organizations/sentry/issues/6709226854/?seerDrawer=true)

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src/sentry/seer/autofix/utils.py

@@ -148,7 +148,11 @@ def get_autofix_state_from_pr_id(provider: str, pr_id: int) -> AutofixState | No
     if not result:
         return None
 
-    return AutofixState.validate(result.get("state", None))
+    state = result.get("state", None)
+    if state is None:
+        return None
+
+    return AutofixState.validate(state)
 
 
 def is_seer_scanner_rate_limited(project: Project, organization: Organization) -> bool: