fix(actions): better runtime check for invalid usages

.changeset/dull-lemons-check.md

@@ -0,0 +1,14 @@
+---
+'astro': patch
+---
+
+Fixes a case where Astro allowed to call an action without using `Astro.callAction`. This is now invalid, and Astro will show a proper error.
+
+```diff
+---
+import { actions } from "astro:actions";
+
+-const result = actions.getUser({ userId: 123 });
++const result = Astro.callAction(actions.getUser, { userId: 123 });
+---
+```

packages/astro/src/actions/runtime/virtual/server.ts

@@ -60,7 +60,8 @@ export function defineAction<
 			: getJsonServerHandler(handler, inputSchema);
 
 	async function safeServerHandler(this: ActionAPIContext, unparsedInput: unknown) {
-		if (typeof this === 'function') {
+		// The ActionAPIContext should always contain the `params` property
+		if (typeof this === 'function' || !('params' in this)) {
 			throw new AstroError(ActionCalledFromServerError);
 		}
 		return callSafely(() => serverHandler(unparsedInput, this));

packages/astro/test/actions.test.js

@@ -132,6 +132,12 @@ describe('Astro Actions', () => {
 				assert.equal(data, 'Hello, ben!');
 			}
 		});
+
+		it('Should fail when calling an action without using Astro.callAction', async () => {
+			const res = await fixture.fetch('/invalid/');
+			const text = await res.text();
+			assert.match(text, /ActionCalledFromServerError/);
+		});
 	});
 
 	describe('build', () => {

packages/astro/test/fixtures/actions/src/pages/invalid.astro

@@ -0,0 +1,6 @@
+---
+import { actions } from "astro:actions";
+
+// this is invalid, it should fail
+const result = await actions.imageUploadInChunks();
+---