[#819] ensure no side effects on SinglepartWriter exception

[donsokolone]

Motivation

Fixes #819

Checklist

Before you create the PR, please make sure you have:

• [x] Picked a concise, informative and complete title
• [x] Clearly explained the motivation behind the PR
• [x] Linked to any existing issues that your PR will be solving
• [x] Included tests for any new functionality
• [x] Checked that all unit tests pass

CC @mpenkov

[ddelange]

@mpenkov can you run CI?

[ddelange]

@mpenkov any chance this one can make next release?

[mpenkov]

Merged. Thank you @donsokolone !