fix build warnings in user app about missing exports in hooks (#1003)

* fix build warnings in user app about missing exports in hooks

* add comment, so we don't make the same mistake again

Co-authored-by: Rich Harris <[email protected]>

Author: Conduitry

.changeset/quiet-ants-report.md

@@ -0,0 +1,5 @@
+---
+'@sveltejs/kit': patch
+---
+
+Fix build warnings about missing exports in hooks file

packages/kit/src/core/build/index.js

@@ -300,11 +300,15 @@ async function build_server(
 				]
 			};
 
-			const hooks = {
-				getContext: user_hooks.getContext || (() => ({})),
-				getSession: user_hooks.getSession || (() => ({})),
-				handle: user_hooks.handle || (({ request, render }) => render(request))
-			};
+			// this looks redundant, but the indirection allows us to access
+			// named imports without triggering Rollup's missing import detection
+			const get_hooks = hooks => ({
+				getContext: hooks.getContext || (() => ({})),
+				getSession: hooks.getSession || (() => ({})),
+				handle: hooks.handle || (({ request, render }) => render(request))
+			});
+
+			const hooks = get_hooks(user_hooks);
 
 			const module_lookup = {
 				${manifest.components.map(file => `${s(file)}: () => import(${s(app_relative(file))})`)}