Using async generator methods leads to syntax errors

Start in esotope.js at the expression-generation logic around lines 1484 and 1513, where async and generator methods are currently treated as mutually exclusive. Reproduce the issue with the async generator example and run the TestCafe tests; done means the generated code preserves both keywords and no longer raises the syntax error.

My application code contains some async generator methods, e.g.:

export default {
  async *generator(param) { /* ... */ }
}

The bundled code is valid and the application starts correctly. However, when running the TestCafe tests, I get a SyntaxError: Unexpected reserved word because the async keyword has been dropped. The reason is that async methods and generator methods are treated as mutually exclusive here and here. To make the TestCafe tests run, I had to patch this library as follows:

diff --git a/node_modules/esotope-hammerhead/esotope.js b/node_modules/esotope-hammerhead/esotope.js
index f8f4a37..dea67f9 100644
--- a/node_modules/esotope-hammerhead/esotope.js
+++ b/node_modules/esotope-hammerhead/esotope.js
@@ -1481,7 +1481,9 @@ var ExprRawGen = {
         }
 
         else {
-            if ($expr.value.generator)
+            if ($expr.value.generator && $expr.value.async)
+                _.js += exprJs + 'async *' + keyJs;
+            else if ($expr.value.generator)
                 _.js += exprJs + '*' + keyJs;
             else if ($expr.value.async)
                 _.js += exprJs + 'async ' + keyJs;
@@ -1510,7 +1512,9 @@ var ExprRawGen = {
                 _.js += keyJs;
 
             else if ($expr.method) {
-                if ($val.generator)
+                if ($val.generator && $val.async)
+                    keyJs = 'async *' + keyJs;
+                else if ($val.generator)
                     keyJs = '*' + keyJs;
                 else if ($val.async)
                     keyJs = 'async ' + keyJs;