fix: library crashes when localStorage is not callable (#342)

Currently, we're checking for localStorage's presence but not its
actual usability. In some scenarios, browsers can disallow
`localStorage` to be called upon and in such cases, the library will hard
crash.

In this change, I added a catch statement to intercept these errors and
return an empty string when `localStorage` cannot be called upon.

- [X] Bug fix (non-breaking change which fixes an issue)
- [ ] New feature (non-breaking change which adds functionality)
- [ ] Breaking change (fix or feature that would cause existing functionality to change)

- [X] I have used ESLint & Prettier to follow the code style of this project.
- [X] I have updated the documentation accordingly.
- [X] I have added tests to cover my changes.
- [X] All new and existing tests passed.

src/components/IntlTelInput.js

@@ -522,13 +522,19 @@ class IntlTelInput extends Component {
     }
   }
 
-  loadAutoCountry = () => {
-    // check for localStorage
-    const lsAutoCountry =
-      window.localStorage !== undefined
+  loadCountryFromLocalStorage = () => {
+    try {
+      return window.localStorage !== undefined
         ? window.localStorage.getItem('itiAutoCountry')
         : ''
+    } catch (e) {
+      return ''
+    }
+  }
 
+  loadAutoCountry = () => {
+    // check for localStorage
+    const lsAutoCountry = this.loadCountryFromLocalStorage()
     if (lsAutoCountry) {
       this.autoCountry = lsAutoCountry
     }

src/components/__tests__/FlagDropDown.test.js

@@ -48,6 +48,25 @@ describe('FlagDropDown', function() {
     })
   })
 
+  it('should fallback to US when localStorage is not available', async () => {
+    const mockedLocalStorage = window.localStorage
+    // This will cause calls to localStorage.getItem() to throw
+    window.localStorage = {}
+
+    this.params = {
+      ...this.params,
+      defaultCountry: 'auto',
+    }
+    const subject = await this.makeSubject()
+
+    subject.instance().utilsScriptDeferred.then(() => {
+      expect(subject.state().countryCode).toBe('us')
+      window.localStorage.clear()
+    })
+
+    window.localStorage = mockedLocalStorage
+  })
+
   it('should has .separate-dial-code class when with separateDialCode = true', () => {
     this.params = {
       ...this.params,