[Fix] no-adjacent-inline-elements: prevent crash on nullish children

Fixes #2620

Author: Rogdham

lib/rules/no-adjacent-inline-elements.js

@@ -84,6 +84,9 @@ module.exports = {
     function validate(node, children) {
       let currentIsInline = false;
       let previousIsInline = false;
+      if (!children) {
+        return;
+      }
       for (let i = 0; i < children.length; i++) {
         currentIsInline = isInline(children[i]);
         if (previousIsInline && currentIsInline) {

tests/lib/rules/no-adjacent-inline-elements.js

@@ -69,6 +69,10 @@ ruleTester.run('no-adjacent-inline-elements', rule, {
       code: '<div><a></a> some text <a></a></div>;',
       parserOptions
     },
+    {
+      code: 'React.createElement("div", null, "some text");',
+      parserOptions
+    },
     {
       code: ('React.createElement("div", undefined, [React.createElement("a"), ' +
         '" some text ", React.createElement("a")]);'),