Coverage dropped when Coverage didn't change

[jcubic]

In this commit:

LIPS-scheme/lips@28a58e6

I've added this code:

    dot = true;
} else if (dot) {
    throw new Error('Parser: syntax error more than one element after dot');
} else {

The code was tested and it's covered by tests, because I checked the JSON file generated by C8 and the lines are green. But Coveralls said that Coverage dropped by -0.02%

https://coveralls.io/builds/65153629

In the same, I deleted one line of code and Coveralls said that the Coverage dropped by 0.002%

https://coveralls.io/builds/65177310

Another example I've updated dependencies and Coverage dropped by 0.3%

https://coveralls.io/builds/65163814

It looks like reports are Random. Can you explain the dropping of Coverage?

This is my coverage status:

----------|---------|----------|---------|---------|
File      | % Stmts | % Branch | % Funcs | % Lines |
----------|---------|----------|---------|---------|
All files |   85.36 |    86.84 |   83.97 |   85.36 |
 lips.js  |   85.36 |    86.84 |   83.97 |   85.36 |
----------|---------|----------|---------|---------|

Not sure why I have 85.669%.

EDIT: Another issue is reverse, the code was added that was fully Tested and Coveralls says that the Coverage increased by 0.02% but nothing changed:

https://coveralls.io/builds/65485219