If original code was TypeScript - the library attempts to read the .ts file as well

[kristijanstefanoski]

I have a TypeScript project which I compile to JavaScript and deploy. It includes source-maps as well, but when I try to apply v8ToIstanbul it fails because it cannot find the .ts file in the src directory - which is not deployed.
Is it expected for this library to have both source and compiled code side-by-side? Or it's just the way I am using it?
Currently I use it in the simplest way possible:
const converter = v8toIstanbul(filePath);

where filePath is the path to the .js file