Describe the bug
I tried to generate lots of random phone numbers locally and at one point noticed nulls in generated strings

To Reproduce
Unfortunately, I can't tell the exact way to reproduce, after restart it came back to normal and I couldn't catch it again

Screenshots
RgxGen props in debug:

Environment (please complete the following information):

• OS: macOS
• JDK/JRE version: 17
• RgxGen Version: 1.4