Fix UnboundLocalError when Core API fails post-update (#6761)

When get_config() raised HomeAssistantError after a Core update, the
except block set error_state and fell through to the frontend check,
which referenced an unbound `data` variable and raised UnboundLocalError.
That aborted the update with a JobException and skipped the rollback
path entirely.

Move the frontend checks into an else branch of the try/except so they
only run when get_config() succeeds. When it fails, error_state is set
and control falls through to the rollback logic below, which is what
PR #6726 intended.

Fixes SUPERVISOR-1JVX

Co-authored-by: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

supervisor/homeassistant/core.py

@@ -332,22 +332,22 @@ class HomeAssistantCore(JobGroup):
             except HomeAssistantError:
                 # The API stopped responding between the update and now
                 self._error_state = True
-
-            # Verify that the frontend is loaded
-            if "frontend" not in data.get("components", []):
-                _LOGGER.error("API responds but frontend is not loaded")
-                self._error_state = True
-            # Check that the frontend is actually accessible
-            elif not await self.sys_homeassistant.api.check_frontend_available():
-                _LOGGER.error(
-                    "Frontend component loaded but frontend is not accessible"
-                )
-                self._error_state = True
             else:
-                # Health checks passed, clean up old image
-                with suppress(DockerError):
-                    await self.instance.cleanup(old_image=old_image)
-                return
+                # Verify that the frontend is loaded
+                if "frontend" not in data.get("components", []):
+                    _LOGGER.error("API responds but frontend is not loaded")
+                    self._error_state = True
+                # Check that the frontend is actually accessible
+                elif not await self.sys_homeassistant.api.check_frontend_available():
+                    _LOGGER.error(
+                        "Frontend component loaded but frontend is not accessible"
+                    )
+                    self._error_state = True
+                else:
+                    # Health checks passed, clean up old image
+                    with suppress(DockerError):
+                        await self.instance.cleanup(old_image=old_image)
+                    return
 
         # Update going wrong, revert it
         if self.error_state and rollback:

tests/api/test_homeassistant.py

@@ -14,6 +14,7 @@ from supervisor.const import DNS_SUFFIX, CoreState
 from supervisor.coresys import CoreSys
 from supervisor.docker.homeassistant import DockerHomeAssistant
 from supervisor.docker.interface import DockerInterface
+from supervisor.exceptions import HomeAssistantError
 from supervisor.homeassistant.api import APIState, HomeAssistantAPI
 from supervisor.homeassistant.const import WSEvent
 from supervisor.homeassistant.core import HomeAssistantCore
@@ -516,3 +517,48 @@ async def test_update_frontend_check_fails_triggers_rollback(
     )
     # Old image should not be cleaned up so rollback doesn't need to re-download
     mock_cleanup.assert_not_called()
+
+
+async def test_update_get_config_error_triggers_rollback(
+    api_client: TestClient,
+    coresys: CoreSys,
+    caplog: pytest.LogCaptureFixture,
+    tmp_supervisor_data: Path,
+):
+    """Test that update triggers rollback when get_config raises HomeAssistantError."""
+    coresys.hardware.disk.get_disk_free_space = lambda x: 5000
+    coresys.homeassistant.version = AwesomeVersion("2025.8.0")
+
+    update_call_count = 0
+
+    async def mock_update(*args, **kwargs):
+        nonlocal update_call_count
+        update_call_count += 1
+        if update_call_count == 1:
+            coresys.homeassistant.version = AwesomeVersion("2025.8.3")
+        elif update_call_count == 2:
+            coresys.homeassistant.version = AwesomeVersion("2025.8.0")
+
+    with (
+        patch.object(DockerInterface, "update", new=mock_update),
+        patch.object(
+            DockerHomeAssistant,
+            "version",
+            new=PropertyMock(return_value=AwesomeVersion("2025.8.0")),
+        ),
+        patch.object(HomeAssistantAPI, "get_config", side_effect=HomeAssistantError),
+        patch.object(
+            HomeAssistantAPI, "check_frontend_available", return_value=True
+        ) as mock_check_frontend,
+        patch.object(DockerInterface, "cleanup") as mock_cleanup,
+    ):
+        resp = await api_client.post("/core/update", json={"version": "2025.8.3"})
+
+    assert resp.status == 200
+    assert "HomeAssistant update failed -> rollback!" in caplog.text
+    assert update_call_count == 2
+    mock_check_frontend.assert_not_called()
+    assert (
+        Issue(IssueType.UPDATE_ROLLBACK, ContextType.CORE) in coresys.resolution.issues
+    )
+    mock_cleanup.assert_not_called()