P1B: Refactor (packages/core/src/session/compaction.ts:86): Function with many returns (count = 6): serialize

### Uniqueness check

- [x] I have searched open issues and confirmed this **file + smell** is not already taken.

### Full path to the Typescript file

packages/core/src/session/compaction.ts

### Function(s)/scope targeted

serialize

### Relevant Qlty output

```shell
packages/core/src/session/compaction.ts
  86  Function with many returns (count = 6): serialize
```