Fix unused internalized async imports (#5652)

* Add test

* Fix

Co-authored-by: Will Binns-Smith <[email protected]>

packages/core/integration-tests/test/integration/scope-hoisting/es6/async-internalize-unused/a.js

@@ -0,0 +1,4 @@
+import c from "./c.js";
+import b from "./b.js";
+
+output = b + c;

packages/core/integration-tests/test/integration/scope-hoisting/es6/async-internalize-unused/b.js

@@ -0,0 +1,3 @@
+import("./c.js");
+
+export default "b";

packages/core/integration-tests/test/integration/scope-hoisting/es6/async-internalize-unused/c.js

@@ -0,0 +1 @@
+export default "c";

packages/core/integration-tests/test/scope-hoisting.js

@@ -167,6 +167,18 @@ describe('scope hoisting', function() {
       assert.deepEqual(output, [123, 123]);
     });
 
+    it('supports async import of internalized asset with unused return value', async function() {
+      let b = await bundle(
+        path.join(
+          __dirname,
+          '/integration/scope-hoisting/es6/async-internalize-unused/a.js',
+        ),
+      );
+
+      let output = await run(b);
+      assert.strictEqual(output, 'bc');
+    });
+
     it('supports importing a namespace of exported values', async function() {
       let b = await bundle(
         path.join(

packages/shared/scope-hoisting/src/link.js

@@ -11,10 +11,10 @@ import type {
 import type {ExternalModule, ExternalBundle} from './types';
 import type {
   Expression,
+  ExpressionStatement,
   File,
   FunctionDeclaration,
   Identifier,
-  Statement,
   StringLiteral,
   VariableDeclaration,
 } from '@babel/types';
@@ -48,9 +48,10 @@ import {
 } from './utils';
 import OutputFormats from './formats/index.js';
 
-const THROW_TEMPLATE = template.statement<{|MODULE: StringLiteral|}, Statement>(
-  '$parcel$missingModule(MODULE);',
-);
+const THROW_TEMPLATE = template.statement<
+  {|MODULE: StringLiteral|},
+  ExpressionStatement,
+>('$parcel$missingModule(MODULE);');
 const REQUIRE_RESOLVE_CALL_TEMPLATE = template.expression<
   {|ID: StringLiteral|},
   Expression,
@@ -678,13 +679,16 @@ export function link({
             }
 
             // async dependency that was internalized
-            if (asyncResolution?.type === 'asset') {
+            if (
+              newNode &&
+              asyncResolution?.type === 'asset' &&
+              !isExpressionStatement(newNode)
+            ) {
               newNode = t.callExpression(
                 t.memberExpression(
                   t.identifier('Promise'),
                   t.identifier('resolve'),
                 ),
-                // $FlowFixMe[incompatible-call]
                 [newNode],
               );
             }