- [x] Switch the reassemble timeout to 5 seconds.
- [x] Print a status message if reassemble fails:

```
Performing hot reload...
Reassembling app.flx$main took too long. Hot reload may have failed.
Reloaded 0 of 418 libraries in 5,322ms.
```

Fixes #9316
Fixes #8861
Fixes #8857
Fixes #8856