fix(compiler): stop error {} from swallowing response {} bugs in api blocks

Client codegen chained .then().catch(), so a .catch() after .then()
caught exceptions thrown by the response body too. Switched to the
two-argument then(onFulfilled, onRejected) form, whose rejection
handler cannot see errors from the fulfilment handler.

SSR codegen wrapped both the transport call and the response-body eval
in the same try; only __wrnexusCallApi is now inside the try, and
__wrnexusEvalData runs after it, outside.

Also verifies (and locks in with a regression test) that GET query
numbers already coerce correctly through defineEndpoint + checkField,
and documents that in the typed-api-block spec.

packages/compiler/test/api-block-ssr.test.ts

@@ -167,6 +167,83 @@ test("an ssr block used in {#each} with an error section runs the error body on
   expect(html).toContain("fallback");
 });
 
+test("an ssr block's response body error is not swallowed by the error section", async () => {
+  const generated = generate(
+    parse(`page Repro {
+  ssr {
+    api ssrUsers GET /api/users {
+      response {
+        return data.users.missing.length
+      }
+      error {
+        return ["fallback"]
+      }
+    }
+  }
+
+  view { <main>{#each ssrUsers as u}<p>{u}</p>{/each}</main> }
+}
+`),
+  );
+
+  const root = mkdtempSync(join(tmpdir(), "wrnexus-ssr-response-throws-"));
+  roots.push(root);
+  mkdirSync(root, { recursive: true });
+  const file = join(root, "page.ts");
+  writeFileSync(file, generated);
+
+  const mod = await import(`${file.replace(/\\/g, "/")}?t=${Date.now()}`);
+
+  await expect(
+    mod.default({
+      req: { url: "http://localhost/", headers: new Headers() },
+      cookies: {},
+      session: {},
+      localStorage: {},
+      __wrnexusCallApi: async () => ({ users: [] }),
+    }),
+  ).rejects.toThrow();
+});
+
+test("an ssr block still runs the error body on a genuine transport failure", async () => {
+  const generated = generate(
+    parse(`page Repro {
+  ssr {
+    api ssrUsers GET /api/users {
+      response {
+        return data.users.length
+      }
+      error {
+        return ["fallback"]
+      }
+    }
+  }
+
+  view { <main>{#each ssrUsers as u}<p>{u}</p>{/each}</main> }
+}
+`),
+  );
+
+  const root = mkdtempSync(join(tmpdir(), "wrnexus-ssr-transport-fails-"));
+  roots.push(root);
+  mkdirSync(root, { recursive: true });
+  const file = join(root, "page.ts");
+  writeFileSync(file, generated);
+
+  const mod = await import(`${file.replace(/\\/g, "/")}?t=${Date.now()}`);
+  const html = await mod.default({
+    req: { url: "http://localhost/", headers: new Headers() },
+    cookies: {},
+    session: {},
+    localStorage: {},
+    __wrnexusCallApi: async () => {
+      throw new Error("boom");
+    },
+  });
+
+  expect(html).toContain("fallback");
+});
+
 test("an ssr block used in {#each} without an error section still propagates a failure", async () => {
   const generated = generate(
     parse(`page Repro {