fix(gateway): guard interface discovery failures

Closes #44180.
Refs #47590.
Co-authored-by: Peter Steinberger <steipete@gmail.com>

src/pairing/setup-code.test.ts

@@ -368,6 +368,27 @@ describe("pairing setup code", () => {
     });
   });
 
+  it("returns a bind-specific error when interface discovery throws", async () => {
+    const resolved = await resolvePairingSetupFromConfig(
+      {
+        gateway: {
+          bind: "lan",
+          auth: { mode: "token", token: "tok" },
+        },
+      },
+      {
+        networkInterfaces: () => {
+          throw new Error("uv_interface_addresses failed");
+        },
+      },
+    );
+
+    expect(resolved).toEqual({
+      ok: false,
+      error: "gateway.bind=lan set, but no private LAN IP was found.",
+    });
+  });
+
   it("prefers gateway.remote.url over tailscale when requested", async () => {
     const runCommandWithTimeout = createTailnetDnsRunner();
 

src/pairing/setup-code.ts

@@ -118,7 +118,12 @@ function pickIPv4Matching(
   networkInterfaces: () => ReturnType<typeof os.networkInterfaces>,
   matches: (address: string) => boolean,
 ): string | null {
-  const nets = networkInterfaces();
+  let nets: ReturnType<typeof os.networkInterfaces>;
+  try {
+    nets = networkInterfaces();
+  } catch {
+    return null;
+  }
   for (const entries of Object.values(nets)) {
     if (!entries) {
       continue;