Adding lots of line breaks to text area

**Describe the bug**
https://www.linkedin.com/posts/-garypalmer_another-day-another-stepwise-change-more-ugcPost-7381969261562478592-_AAc go to this post in Firefox 143.0.4 (aarch64) and try to comment "ga", as two letters doesn't mean anything I think Harper tries to underline it as error but instead adds lots of empty line breaks at the end, like almost infinite amount.

**To Reproduce**
Steps to reproduce the behavior:
1. In Firefox 143.0.4 (aarch64) go to https://www.linkedin.com/posts/-garypalmer_another-day-another-stepwise-change-more-ugcPost-7381969261562478592-_AAc
2. Click on comment box
3. Type "ga" (2 letters, I think anything will work that is grammatically not meaningful)
4. See error

**Expected behavior**
Drawing underline as error

**Screenshots**

**Platform**
MacBook M1 Pro - macOS 15.7.1 (24G231) - Firefox 143.0.4 (aarch64)

Start by reproducing the issue at the linked LinkedIn post in Firefox 143.0.4 on macOS, following the comment-box steps and typing "ga". Trace the textarea integration responsible for rendering grammar errors; done means the text remains unchanged apart from the expected underline and no extra line breaks are inserted.

Written by the indexing model from the issue text.