Bug with saving empty text run value.

• Rive desktop version on mac - BETA 0.8.1986

To reproduce:

1. Create a text with a initial text run value.

2. Change it by removing the default "text" value in text run

3. Close the document and open it again

4. The value is replaced by a previous value instead of being empty.

The empty value works if using whitespace or new line. Not sure if this is by design tho. Let me know.