fix: remove ExportNamedDeclaration when the specifier is empty (#10638)

packages/babel-plugin-transform-modules-systemjs/src/index.js

@@ -413,6 +413,8 @@ export default declare((api, options) => {
 
                     path.replaceWithMultiple(nodes);
                   }
+                } else {
+                  path.remove();
                 }
               }
             }

packages/babel-plugin-transform-modules-systemjs/test/fixtures/systemjs/export-named-8/input.mjs

@@ -0,0 +1 @@
+export {}

packages/babel-plugin-transform-modules-systemjs/test/fixtures/systemjs/export-named-8/output.mjs

@@ -0,0 +1,8 @@
+System.register([], function (_export, _context) {
+  "use strict";
+
+  return {
+    setters: [],
+    execute: function () {}
+  };
+});