Two small fixes:
1. **iterationitem.py line 72**: Typo "interationitem" → "iterationitem"
(missing 't'). The component name check never matched IterationItem
components.
2. **raptor.py line 94**: Error message "Embedding error: " had a
trailing colon with no details. Changed to "Embedding error: empty
embeddings returned".
### What problem does this PR solve?
Add mechanism to check cancellation in Agent.
### Type of change
- [x] New Feature (non-breaking change which adds functionality)
### What problem does this PR solve?
#9082#6365
<u> **WARNING: it's not compatible with the older version of `Agent`
module, which means that `Agent` from older versions can not work
anymore.**</u>
### Type of change
- [x] New Feature (non-breaking change which adds functionality)
