Capitalization with empty keys

[PyvesB]

This pull request addresses issue #1606. We now also have some tests for the social badge template!

[shields-ci]

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[RedSparr0w]

Thanks for this PR, you've been making a ton of progress through all the errors recently!
Unfortunately i don't think this will fix #1606
for undefined it will still throw Uncaught TypeError: Cannot read property 'charAt' of undefined
for numbers it will throw Uncaught TypeError: s.charAt is not a function

something like this should work:

-function capitalize(s) {
+function capitalize(s = '') {
+	s = '' + s;
	return s.charAt(0).toUpperCase() + s.slice(1);
}

Output:

capitalize(undefined); // ""
capitalize(2); // "2"
capitalize(false); // "False"
capitalize('test'); // "Test"

---

Edit:

Didn't realise it was undefined due to trying to get the first character using [0] of '', nice work!
👍

[PyvesB]

Yes, the input s can be empty (which was causing the crash), but cannot itself be undefined due to a string coercion step before the call to capitalize:

  // String coercion.
  text = text.map(value => '' + value);