Survive a missing xdg-open during login

packages/core/src/net/oauth2.ts

@@ -75,6 +75,12 @@ export async function openBrowser(url: string): Promise<void> {
   const args = process.platform === "win32" ? ["/c", "start", "", url] : [url];
   try {
     const child = spawn(command, args, { stdio: "ignore", detached: true });
+    // A missing opener (a server with no xdg-open) is reported here, on a
+    // later tick, not by throwing. Unhandled, that event ends the process
+    // right after the authorize link has been printed.
+    child.on("error", () => {
+      /* the caller prints the URL too */
+    });
     child.unref();
   } catch {
     /* the caller prints the URL too */

packages/core/test/open-browser.test.ts

@@ -0,0 +1,33 @@
+/**
+ * Raising a browser must never take the login down with it.
+ *
+ * On a server with no desktop there is no xdg-open. spawn() reports that as an
+ * asynchronous "error" event, not a throw, so the try/catch around it caught
+ * nothing and the unhandled event killed `myna login x` a moment after it had
+ * printed the paste-the-code prompt. The link was already on screen; the user
+ * only needed the process to stay alive.
+ */
+import { test, expect } from "bun:test";
+import { EventEmitter } from "node:events";
+import { mkdtempSync } from "node:fs";
+import { tmpdir } from "node:os";
+import { join } from "node:path";
+import { openBrowser } from "../src/net/oauth2.ts";
+
+test("a missing browser opener is not fatal", async () => {
+  const path = process.env.PATH;
+  const uncaught: unknown[] = [];
+  const catchAll = (error: unknown) => { uncaught.push(error); };
+  process.env.PATH = mkdtempSync(join(tmpdir(), "myna-nopath-"));
+  process.on("uncaughtException", catchAll);
+  try {
+    await openBrowser("https://example.test/authorize");
+    // The spawn error arrives on a later tick; give it time to surface.
+    await new Promise((resolve) => setTimeout(resolve, 100));
+  } finally {
+    process.env.PATH = path;
+    // Bun types process.removeListener more narrowly than process.on.
+    (process as unknown as EventEmitter).removeListener("uncaughtException", catchAll);
+  }
+  expect(uncaught).toEqual([]);
+});