Bug: Operating panics when a 404 error injection is added.

### Minimal reproduce step

The steps to reproduce the panic are as follows: First, add a 404 error fault injection within the Operating environment. Subsequently, increase the replica count from 3 to 6; the newly added 3 pods will fail to be created. Then, disable the fault injection and alter the replica count to 4; this action will trigger a panic in the Operating system.

### What did you expect to see?

When simulating exceptions in Operating, including but not limited to errors such as 404, 503, etc., Operating still runs stably.

### What did you see instead

Operating is panic.

### What is your KusionStack components and its version?

As follows:

Start by reproducing the sequence: add a 404 fault injection, increase replicas from 3 to 6, disable the injection, and reduce replicas to 4. Trace the resulting panic in the Operating environment and verify that changing replica counts remains stable with simulated 404 and 503 errors.

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