Add comment explaining try/catch

Author: Joachim Seminck

lib/util/Components.js

@@ -216,6 +216,8 @@ function componentRule(rule, context) {
      */
     isExplicitComponent: function(node) {
       let comment;
+      // Sometimes the passed node may not have been parsed yet by eslint, and this function call crashes.
+      // Can be removed when eslint sets "parent" property for all nodes on initial AST traversal: https://github.com/eslint/eslint-scope/issues/27
       try {
         comment = sourceCode.getJSDocComment(node);
       } catch (e) {