fix function scanner #3

Author: oscarotero

src/JsNodeVisitor.php

@@ -87,7 +87,12 @@ protected static function getFunctionName(CallExpression $node): ?string
             case 'Identifier':
                 return $callee->getName();
             case 'MemberExpression':
-                return $callee->getProperty()->getName();
+                $property = $callee->getProperty();
+
+                if ($property->getType() === 'Identifier') {
+                    return $property->getName();
+                }
+                return null;
             default:
                 return null;
         }

tests/assets/functions.js

@@ -27,4 +27,7 @@ fn9(ARG_8);
        /* No Related comment 4 */
     );
 })
-fn13(fn14(fn15('foo')));
+fn13(fn14(fn15('foo')));
+
+// https://github.com/php-gettext/JS-Scanner/issues/3
+var REACT_ELEMENT_TYPE = typeof Symbol === 'function' && Symbol['for'] && Symbol['for']('react.element') || 0xeac7;