Fix NPE with horse racing emoji check

Fix https://gitlab.com/gitlab-org/gitlab-ce/issues/32587

app/assets/javascripts/behaviors/gl_emoji.js

@@ -88,6 +88,7 @@ function installGlEmojiElement() {
     const hasCssSpriteFalback = fallbackSpriteClass && fallbackSpriteClass.length > 0;
     if (
+      emojiUnicode &&
       isEmojiUnicode &&
       !isEmojiUnicodeSupported(generatedUnicodeSupportMap, emojiUnicode, unicodeVersion)
     ) {

app/assets/javascripts/behaviors/gl_emoji/is_emoji_unicode_supported.js

@@ -28,7 +28,8 @@ function isSkinToneComboEmoji(emojiUnicode) {
 // doesn't support the skin tone versions of horse racing
 const horseRacingCodePoint = 127943;// parseInt('1F3C7', 16)
 function isHorceRacingSkinToneComboEmoji(emojiUnicode) {
-  return Array.from(emojiUnicode)[0].codePointAt(0) === horseRacingCodePoint &&
+  const firstCharacter = Array.from(emojiUnicode)[0];
+  return firstCharacter && firstCharacter.codePointAt(0) === horseRacingCodePoint &&
     isSkinToneComboEmoji(emojiUnicode);
 }