Weird behavior when typing asterisks ("*")

### Disclaimer
First of all, I wish I knew how to solve this bug. I'm a beginner-level programmer, but I have zero experience on Electron or Swift, that's why I decided to open this issue.

### Expected
When I type, for example, three asterisks in a row and then I hit Enter/Return, I expect it to show three asteriks and then take me to the next line.

### Observed
Instead, Simplenote for macOS (either Mojave and Catalina) shows 3 asterisks in the first line, and 1 extra asterisk in the next line.

### Reproduced
> 1. Open Simplenote
> 2. Open a new note (or start a new line)
> 3. Type one or more asterisks
> 4. Hit enter


Make|Model|macOS Version|App Version
-|-|-|-
SYSTEM_MAKE|MacBook Air (Late 2015)|macOS 10.15.3 (Catalina) | Simplenote 1.9.1

Reproduce the asterisk and Return-key behavior in Simplenote for macOS using the listed macOS and app versions. No source file, test, or entry point is named; trace the macOS text-input handling and confirm that the extra asterisk no longer appears on the next line.

Written by the indexing model from the issue text.