## Summary of the Pull Request
When `GenHTML` or `GenRTF` encountered an empty line, they assumed that `CR` is the last character of the row and wrote it, even though in general `CR` and `LF` just break the line and instead of them either `<BR>` in HTML or `\line` in RTF is written. Don't know how I missed that in #2038.
Another question is whether the `TextAndColor` structure which these methods receive and which is generated by `TextBuffer::GetTextForClipboard` should really contain `\r\n` at the end of each row. I think it'd be cleaner if it didn't esp. that afaik these last 2 characters don't have associated valid color information.
## References
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## PR Checklist
* [X] Closes#4187
* [X] CLA signed. If not, go over [here](https://cla.opensource.microsoft.com/microsoft/Terminal) and sign the CLA
* [ ] Tests added/passed - there aren't any related tests, right?
* [ ] Requires documentation to be updated
* [ ] I've discussed this with core contributors already. If not checked, I'm ready to accept this work might be rejected in favor of a different grand plan. Issue number where discussion took place: #4147
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## Validation Steps Performed
Copied various terminal states and verified the generated HTML.
1ca29128d4