[Bug] divide by zero panic after exiting test

I am using ttyper 0.4.0 and I have encountered a panic after escaping during test I don't know what causes it and i can't replicate it

```
thread 'main' panicked at 'attempt to divide by zero', /home/eco/.local/share/cargo/registry/src/github.com-1ecc6299db9ec823/tui-0.16.0/src/widgets/chart.rs:425:22
```