Only reference helpers from external helpers or runtime helpers if they are known to be available.

packages/babel-plugin-external-helpers/src/index.js

@@ -1,12 +1,24 @@
 import { declare } from "@babel/helper-plugin-utils";
 import { types as t } from "@babel/core";
 
-export default declare(api => {
+export default declare((api, options) => {
   api.assertVersion(7);
 
+  const { helperVersion = "7.0.0-beta.0" } = options;
+
   return {
     pre(file) {
       file.set("helperGenerator", name => {
+        // If the helper didn't exist yet at the version given, we bail
+        // out and let Babel either insert it directly, or throw an error
+        // so that plugins can handle that case properly.
+        if (
+          file.availableHelper &&
+          !file.availableHelper(name, helperVersion)
+        ) {
+          return;
+        }
+
         return t.memberExpression(
           t.identifier("babelHelpers"),
           t.identifier(name),