Fix codecov

[apertureless]

Somehow codecov shows 100% coverage.

But not all functions are covered.

----------|----------|----------|----------|----------|----------------|
File      |  % Stmts | % Branch |  % Funcs |  % Lines |Uncovered Lines |
----------|----------|----------|----------|----------|----------------|
All files |      100 |      100 |       40 |      100 |                |
 index.js |      100 |      100 |       40 |      100 |                |
----------|----------|----------|----------|----------|----------------|