Cannot read property 'toString' of null

[vinaynb]

I am using gulp istanbul in CI cycle to run automated unit tests code coverage. I am getting this error when running my tests inside a docker container. I am sure as this has something to do with my docker env as there is no error when i modify the dockerfile in certain way (removing a specific command) but i need to keep it that way and hence i need to understand what this error means. Hopefully the reason for this error will give me right pointers to debug my docker commands.

The command in question is cp -R node_modules prod_node_modules

[ghost]

@vinaynb Did you find the reason and solution for this error?

[cowwoc]

In my case this was caused by the following code:

return gulp.src(["src/**/*.ts"], {read: false}).
  pipe(istanbul()).
  pipe(istanbul.hookRequire());

The key here is read: false which causes gulp to send istanbul a list of files, but leaves their contents as null. Removing read: false fixed the problem for me.