Fix `execution_count`, and only show `new_data` if it not empty

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 79.72%. Comparing base (5937b88) to head (516e24c). Report is 56 commits behind head on main.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #273 +/- ## ========================================== + Coverage 75.75% 79.72% +3.97% ========================================== Files 70 65 -5 Lines 4615 4908 +293 ========================================== + Hits 3496 3913 +417 + Misses 1119 995 -124 ``` | [Flag](https://app.codecov.io/gh/aiidateam/aiida-workgraph/pull/273/flags?src=pr&el=flags&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=aiidateam) | Coverage Δ | | |---|---|---| | [python-3.11](https://app.codecov.io/gh/aiidateam/aiida-workgraph/pull/273/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=aiidateam) | `79.64% <100.00%> (+3.97%)` | :arrow_up: | | [python-3.12](https://app.codecov.io/gh/aiidateam/aiida-workgraph/pull/273/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=aiidateam) | `79.64% <100.00%> (?)` | | | [python-3.9](https://app.codecov.io/gh/aiidateam/aiida-workgraph/pull/273/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=aiidateam) | `79.68% <100.00%> (+3.94%)` | :arrow_up: | Flags with carried forward coverage won't be shown. [Click here](https://docs.codecov.io/docs/carryforward-flags?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=aiidateam#carryforward-flags-in-the-pull-request-comment) to find out more.

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