getPolyfillString emits invalid environment warning when used as library

[cdaringe]

What

getPolyfillString() emits an ENV warning in the emitted javascript, against expectation.

I call getPolyfillString from library code, not via a service, however, getPolyfillString assumes it's being run as a service, and reads the ENV vs its passed params.

I cannot mutate NODE_ENV to "production" in my library, as other references are coupled to NODE_ENV as well. Global mutations are also discouraged as general programming practice, and my library is permissible to use in development.

Details

describe what the expected behaviour is, and what is actually happening

expected: The emitted code emits no environment warning in the emitted javascript
actual: The emitted code emits an environment warning in the emitted javascript

getPolyfillString can be a pure function, but has implicit coupling to being attached to the pf.io service

add steps on how to reproduce it

Call getPolyfillString() with a non-production NODE_ENV, observe JS output

explain what alternatives you have explored / considered

Permit appVersionText to be configurable here.

example:

const appVersionText = options.appVersionText 
  ? options.appVersionText 
  : "Polyfill service " +
  (process.env.NODE_ENV === "production"
    ? "v" + appVersion
    : "DEVELOPMENT MODE - for live use set NODE_ENV to 'production'")