[fix] Migration fixes (#6096)

* handle error without message

* handle GET without body (which is wrong, but people could have that)

* automigrate status 200 in load

* changeset

Author: dummdidumm

.changeset/olive-ducks-talk.md

@@ -0,0 +1,5 @@
+---
+'svelte-migrate': patch
+---
+
+Handle Error without message, handle status 200, handle missing body

packages/migrate/migrations/routes/migrate_page_js/index.js

@@ -61,8 +61,12 @@ export function migrate_page(content, filename) {
 						return; // nothing to do
 					}
 
-					if (keys === 'props') {
-						automigration(value, file.code, dedent(nodes.props.getText()));
+					if (
+						keys === 'props' ||
+						((keys === 'status' || keys === 'props status') &&
+							Number(nodes.status.getText()) === 200)
+					) {
+						automigration(value, file.code, dedent(nodes.props?.getText() || ''));
 						return;
 					}
 
@@ -85,10 +89,16 @@ export function migrate_page(content, filename) {
 						if (nodes.error) {
 							const message = is_string_like(nodes.error)
 								? nodes.error.getText()
-								: is_new(nodes.error, 'Error') && nodes.error.arguments[0].getText();
-
-							if (message) {
-								automigration(node, file.code, `throw error(${status || 500}, ${message});`);
+								: is_new(nodes.error, 'Error')
+								? /** @type {string | undefined} */ (nodes.error.arguments[0]?.getText())
+								: false;
+
+							if (message !== false) {
+								automigration(
+									node,
+									file.code,
+									`throw error(${status || 500}${message ? `, ${message}` : ''});`
+								);
 								imports.add('error');
 								return;
 							}

packages/migrate/migrations/routes/migrate_page_js/samples.md

@@ -157,6 +157,29 @@ export function load({ session }) {
 }
 ```
 
+## Error constructor with no arguments
+
+```js before
+export function load({ session }) {
+	if (!session.user?.admin) {
+		return {
+			status: 403,
+			error: new Error()
+		};
+	}
+}
+```
+
+```js after
+import { error } from '@sveltejs/kit';
+
+export function load({ session }) {
+	if (!session.user?.admin) {
+		throw error(403);
+	}
+}
+```
+
 ## Error status with no error
 
 ```js before
@@ -322,3 +345,36 @@ export function load() {
 	return;
 }
 ```
+
+## A load function that returns props and status 200
+
+```js before
+export function load() {
+	return {
+		status: 200,
+		props: {}
+	};
+}
+```
+
+```js after
+export function load() {
+	return {};
+}
+```
+
+## A load function that returns status 200
+
+```js before
+export function load() {
+	return {
+		status: 200 
+	};
+}
+```
+
+```js after
+export function load() {
+	return ;
+}
+```

packages/migrate/migrations/routes/migrate_page_server/index.js

@@ -58,7 +58,7 @@ export function migrate_page_server(content, filename) {
 							return;
 						}
 
-						automigration(value, file.code, dedent(nodes.body.getText()));
+						automigration(value, file.code, dedent(nodes.body?.getText() || ''));
 					});
 				}
 

packages/migrate/migrations/routes/migrate_page_server/samples.md

@@ -137,3 +137,19 @@ export function load() {
 	return;
 }
 ```
+
+## A function that wrongfully has no body
+
+```js before
+export function GET() {
+	return {
+		status: 200
+	};
+}
+```
+
+```js after
+export function load() {
+	return ;
+}
+```