## What
- make `Switch` ignore conditions that have no evaluable items
- add a regression for blank `cpn_id` items falling through to the else
branch
- keep the existing non-empty `and` condition behavior covered
Fixes#15643.
## Verified
- `python -m py_compile agent\component\switch.py
test\unit_test\agent\component\test_switch.py`
- `python -m pytest test\unit_test\agent\component\test_switch.py -q` ->
`2 passed`
- `python -m ruff check agent\component\switch.py
test\unit_test\agent\component\test_switch.py`
- `git diff --check`
I also checked `python -m ruff format --check` on the touched files. It
would reformat pre-existing style in `agent/component/switch.py` beyond
this bug fix, so I kept the patch scoped instead of reformatting the
whole file.
\`switch.py\` line 137 concatenates the operator directly after the text
without separator:
\`'Not supported operator' + operator\` → produces \`"Not supported
operatorXXX"\`
Changed to: \`f'Not supported operator: {operator}'\`
### 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?
issue：#5617
change：add IBM DB2 support in ExeSQL
### 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)
