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-codegen.test.ts

@@ -1,7 +1,15 @@
-import { expect, test } from "bun:test";
+import { afterEach, expect, test } from "bun:test";
+import { mkdirSync, mkdtempSync, rmSync, writeFileSync } from "node:fs";
+import { tmpdir } from "node:os";
+import { join } from "node:path";
 import { parse } from "@wrnexus/syntax";
 import { generateTargets } from "../src/targets.ts";
 
+const roots: string[] = [];
+afterEach(() => {
+  for (const root of roots.splice(0)) rmSync(root, { recursive: true, force: true });
+});
+
 function browserModule(inner: string): string {
   return generateTargets(
     parse(`page Repro {
@@ -143,6 +151,111 @@ test("a page with state api and no client api blocks still reads that state (B5)
   }).not.toThrow();
 });
 
+/**
+ * Builds a browser module whose `run()` function calls api.searchUsers and
+ * reports the outcome through `output.report(...)` so the test can observe
+ * whether the call resolved or rejected without reaching into codegen
+ * internals.
+ */
+function reportingBrowserModule(apiBlock: string): string {
+  return generateTargets(
+    parse(`page Repro {
+  client {
+${apiBlock}
+  }
+
+  outputs {
+    report(payload: any)
+  }
+
+  functions {
+    client async function run(): Promise<void> {
+      try {
+        const users = await api.searchUsers({ name: "Ajay" })
+        output.report({ ok: true, users })
+      } catch (e) {
+        output.report({ ok: false, message: String(e && e.message || e) })
+      }
+    }
+  }
+
+  view { <main><button @click="run()">go</button></main> }
+}
+`),
+  ).browser;
+}
+
+async function importBrowserModule(source: string): Promise<any> {
+  const root = mkdtempSync(join(tmpdir(), "wrnexus-client-exec-"));
+  roots.push(root);
+  mkdirSync(root, { recursive: true });
+  const file = join(root, "page.mjs");
+  writeFileSync(file, source);
+  return import(`${file.replace(/\\/g, "/")}?t=${Date.now()}`);
+}
+
+test("a response body error is not swallowed by the error section (client)", async () => {
+  const mod = await importBrowserModule(
+    reportingBrowserModule(`    api searchUsers GET /api/users {
+      request { parameters { name: string } }
+      response {
+        return data.users.missing.length
+      }
+      error {
+        return []
+      }
+    }`),
+  );
+
+  const reports: unknown[] = [];
+  const context = {
+    state: {},
+    props: {},
+    output: { report: (value: unknown) => reports.push(value) },
+    server: {},
+    refs: {},
+    callApi: async () => ({ users: [] }),
+  };
+
+  await mod.__wrnexusClientFunctions.run(context);
+
+  expect(reports).toEqual([{ ok: false, message: expect.any(String) }]);
+  // The error section's own fallback ("[]" / an empty array) must not have
+  // been what the caller observed -- a bug in the response body is a
+  // rejection, not a silently-returned fallback value.
+  expect(reports[0]).not.toEqual({ ok: true, users: [] });
+});
+
+test("a genuine transport failure still runs the error section's fallback (client)", async () => {
+  const mod = await importBrowserModule(
+    reportingBrowserModule(`    api searchUsers GET /api/users {
+      request { parameters { name: string } }
+      response {
+        return data.users
+      }
+      error {
+        return ["fallback"]
+      }
+    }`),
+  );
+
+  const reports: unknown[] = [];
+  const context = {
+    state: {},
+    props: {},
+    output: { report: (value: unknown) => reports.push(value) },
+    server: {},
+    refs: {},
+    callApi: async () => {
+      throw Object.assign(new Error("transport failed"), { status: 500 });
+    },
+  };
+
+  await mod.__wrnexusClientFunctions.run(context);
+
+  expect(reports).toEqual([{ ok: true, users: ["fallback"] }]);
+});
+
 test("a state field named api does not collide with the emitted api object", () => {
   const generated = generateTargets(
     parse(`page Repro {