Jest + React Testing Library error

### Description

Hi!

Trying to test my code with Jest + React Testing Library and getting the error below. Seems it's related to issue #97.

I've seen you made a fix here https://github.com/alvarotrigo/react-fullpage/compare/v0.1.8...v0.1.11#diff-545931490bc9fb7bfb72fcc1db6fbf41916a8b0b67a1ae9289c7a7df84d32424 but I noticed that after source code building ` process.env.NODE_ENV.toLowerCase()` becoming `var env="production".toLowerCase()`. It means env always asserts to 'production' even in a test environment. You can check this in the latest release https://github.com/alvarotrigo/react-fullpage/releases/tag/0.1.18

```error:
Error: Uncaught [TypeError: Cannot read property 'length' of undefined]
at reportException (/Use...
"Error: Uncaught [TypeError: Cannot read property 'length' of undefined]\n at reportException (/Users/aliaksandrihnashevich/PhpstormProjects/appshell-frontend/node_modules/jsdom/lib/jsdom/living/helpers/runtime-script-errors.js:62:24)\n at innerInvokeEventListeners (/Users/aliaksandrihnashevich/PhpstormProjects/appshell-frontend/node_modules/jsdom/lib/jsdom/living/events/EventTarget-impl.js:333:9)\n at invokeEventListeners (/Users/aliaksandrihnashevich/PhpstormProjects/appshell-frontend/node_modules/jsdom/lib/jsdom/living/events/EventTarget-impl.js:274:3)\n at HTMLUnknownElementImpl._dispatch (/Users/aliaksandrihnashevich/PhpstormProjects/appshell-frontend/node_modules/jsdom/lib/jsdom/living/events/EventTarget-impl.js:221:9)\n at HTMLUnknownElementImpl.dispatchEvent (/Users/aliaksandrihnashevich/PhpstormProjects/appshell-frontend/node_modules/jsdom/lib/jsdom/living/events/EventTarget-impl.js:94:17)\n at HTMLUnknownElement.dispatchEvent (/Users/aliaksandrihnashevich/PhpstormProjects/appshell-frontend/node_modules/jsdom/lib/jsdom/living/generated/EventTarget.js:231:34)\n at Object.invokeGuardedCallbackDev (/Users/aliaksandrihnashevich/PhpstormProjects/appshell-frontend/modules/TraderProgram/node_modules/react-dom/cjs/react-dom.development.js:237:16)\n at invokeGuardedCallback (/Users/aliaksandrihnashevich/PhpstormProjects/appshell-frontend/modules/TraderProgram/node_modules/react-dom/cjs/react-dom.development.js:292:31)\n at commitRootImpl (/Users/aliaksandrihnashevich/PhpstormProjects/appshell-frontend/modules/TraderProgram/node_modules/react-dom/cjs/react-dom.development.js:22541:9)\n at unstable_runWithPriority (/Users/aliaksandrihnashevich/PhpstormProjects/appshell-frontend/modules/TraderProgram/node_modules/scheduler/cjs/scheduler.development.js:653:12)"
Cannot read property 'length' of undefined...
{}
Error: Uncaught [TypeError: Cannot read property 'destroy' of undefined]
at reportException (/Us...
"Error: Uncaught [TypeError: Cannot read property 'destroy' of undefined]\n at reportException (/Users/aliaksandrihnashevich/PhpstormProjects/appshell-frontend/node_modules/jsdom/lib/jsdom/living/helpers/runtime-script-errors.js:62:24)\n at innerInvokeEventListeners (/Users/aliaksandrihnashevich/PhpstormProjects/appshell-frontend/node_modules/jsdom/lib/jsdom/living/events/EventTarget-impl.js:333:9)\n at invokeEventListeners (/Users/aliaksandrihnashevich/PhpstormProjects/appshell-frontend/node_modules/jsdom/lib/jsdom/living/events/EventTarget-impl.js:274:3)\n at HTMLUnknownElementImpl._dispatch (/Users/aliaksandrihnashevich/PhpstormProjects/appshell-frontend/node_modules/jsdom/lib/jsdom/living/events/EventTarget-impl.js:221:9)\n at HTMLUnknownElementImpl.dispatchEvent (/Users/aliaksandrihnashevich/PhpstormProjects/appshell-frontend/node_modules/jsdom/lib/jsdom/living/events/EventTarget-impl.js:94:17)\n at HTMLUnknownElement.dispatchEvent (/Users/aliaksandrihnashevich/PhpstormProjects/appshell-frontend/node_modules/jsdom/lib/jsdom/living/generated/EventTarget.js:231:34)\n at Object.invokeGuardedCallbackDev (/Users/aliaksandrihnashevich/PhpstormProjects/appshell-frontend/modules/TraderProgram/node_modules/react-dom/cjs/react-dom.development.js:237:16)\n at invokeGuardedCallback (/Users/aliaksandrihnashevich/PhpstormProjects/appshell-frontend/modules/TraderProgram/node_modules/react-dom/cjs/react-dom.development.js:292:31)\n at safelyCallComponentWillUnmount (/Users/aliaksandrihnashevich/PhpstormProjects/appshell-frontend/modules/TraderProgram/node_modules/react-dom/cjs/react-dom.development.js:19587:5)\n at commitUnmount (/Users/aliaksandrihnashevich/PhpstormProjects/appshell-frontend/modules/TraderProgram/node_modules/react-dom/cjs/react-dom.development.js:20109:11)"
Cannot read property 'destroy' of undefined...
{}
The above error occurred in the component:
in ReactFullpage (created by TraderPr...
"The above error occurred in the component:\n in ReactFullpage (created by TraderProgramDesktop)\n in TraderProgramDesktop\n in div (created by Context.Consumer)\n in Media\n in Unknown\n in Provider\n in IntlProvider\n in Unknown\n\nConsider adding an error boundary to your tree to customize error handling behavior.\nVisit https://fb.me/react-error-boundaries to learn more about error boundaries."
The above error occurred in the component:
in ReactFullpage (created by TraderPr...
"The above error occurred in the component:\n in ReactFullpage (created by TraderProgramDesktop)\n in TraderProgramDesktop\n in div (created by Context.Consumer)\n in Media\n in Unknown\n in Provider\n in IntlProvider\n in Unknown\n\nConsider adding an error boundary to your tree to customize error handling behavior.\nVisit https://fb.me/react-error-boundaries to learn more about error boundaries."```

Chrome: Version 91.0.4472.114 (Official Build) (x86_64)
MacOS: BigSur
Node: v14.17.0