ContainerSvc: Handle unexpected sandbox svc exits (apple#1065)

Closes apple#1050

If the sandbox svc exits out of band of the usual stop (or regular exit)
case the container svc's state is not properly updated for the
container. This was due to the cleanup steps involving trying to send
the shutdown rpc which cannot succeed as the sandbox svc does not exist
to service it.

To handle this, let's treat shutdown not returning successfully as
non-fatal (as this is mostly best effort), log an error and continue the
state cleanup.

Author: dcantah

Sources/Services/ContainerAPIService/Server/Containers/ContainersService.swift

@@ -544,12 +544,26 @@ public actor ContainersService {
             instanceId: id
         )
 
-        let client = try state.getClient()
-        try await client.shutdown()
+        // Try to shutdown the client gracefully, but if the sandbox service
+        // is already dead (e.g., killed externally), we should still continue
+        // with state cleanup.
+        if let client = state.client {
+            do {
+                try await client.shutdown()
+            } catch {
+                self.log.error("Failed to shutdown sandbox service for \(id): \(error)")
+            }
+        }
 
-        // Deregister the service, launchd will terminate the process
-        try ServiceManager.deregister(fullServiceLabel: label)
-        self.log.info("Deregistered sandbox service for \(id)")
+        // Deregister the service, launchd will terminate the process.
+        // This may also fail if the service was already deregistered or
+        // the process was killed externally.
+        do {
+            try ServiceManager.deregister(fullServiceLabel: label)
+            self.log.info("Deregistered sandbox service for \(id)")
+        } catch {
+            self.log.error("Failed to deregister sandbox service for \(id): \(error)")
+        }
 
         state.snapshot.status = .stopped
         state.snapshot.networks = []