#### Summary:
When thousands of objects are selected, extensions will fail with `Script::execute() failed to execute program 'path\to\pythonw.exe'. Reasons: Failed to execute helper program (Invalid argument)`
#### Steps to reproduce:
<!-- Describe what you did (step-by-step) so we can reproduce: -->
- open Inkscape
- Select thousands of objects
- Run a blank extension that does nothing
#### What happened?
- if you're running inkscape.com, you should get the warning `Script::execute() failed to execute program 'path\to\pythonw.exe'. Reasons: Failed to execute helper program (Invalid argument)` and the extension does not run.
- ~~The extension will freeze, saying "'Extension' working, please wait..."~~ Fixed by https://gitlab.com/inkscape/inkscape/-/merge_requests/3584
#### What should have happened?
The extension should have run successfully
Sample attachments:
<!-- Attach the sample file(s) highlighting the issue, if appropriate. -->
A file with 8970 selectable objects:
An Effect extension and INX file that do nothing:
[fuse_by_color.py](/uploads/52ae79fe57605f7cb15fe1640fa003d5/fuse_by_color.py)[fuse_by_color.inx](/uploads/693023a4003f702cbfc4b0c5659ea69e/fuse_by_color.inx)
#### Version Info:
```
- Inkscape Version: 1.0.2-2 (e86c870879, 2021-01-15)
- Operating System: Windows 10 Enterprise
- Operating System version: 1909
```
<!--
❤️ Thank you for filling in a new bug report, we appreciate the help! ❤️
Please be patient while we try to find the time to look into your issue.
Remember that Inkscape is developed by volunteers in their spare time, we'll try our best to respond to all reports.
-->
<!--
Please be careful when/after writing # for example in logs, code, or versions of linux
- use inline code span - single backticks (`) before and after it, like this - `inbox#1618`
- use multi-line code block - triple backticks (```) to fence/enclose console logs
- attach long logs as a text file.
-->
