Fix dangling log pointer in PackageManager after resolve

src/bun.js/VirtualMachine.zig

@@ -1840,6 +1840,12 @@ pub fn resolveMaybeNeedsTrailingSlash(
         jsc_vm.log = old_log;
         jsc_vm.transpiler.linker.log = old_log;
         jsc_vm.transpiler.resolver.log = old_log;
+        // The package manager may have been initialized during this resolve
+        // with a pointer to the stack-local `log`. Restore it so it doesn't
+        // dangle after this frame returns.
+        if (jsc_vm.transpiler.resolver.package_manager) |pm| {
+            pm.log = old_log;
+        }
     }
     jsc_vm._resolve(&result, specifier_utf8.slice(), normalizeSource(source_utf8.slice()), is_esm, is_a_file_path) catch |err_| {
         var err = err_;

test/js/bun/test/mock/mock-module-resolve-crash.test.ts

@@ -0,0 +1,31 @@
+import { expect, test } from "bun:test";
+import { bunEnv, bunExe } from "harness";
+
+// Regression test: mock.module with a non-string specifier (e.g. Intl.Segmenter)
+// used to cause a stack-buffer-overflow because the PackageManager singleton could
+// capture a dangling pointer to a stack-local Log during module resolution.
+test("mock.module with non-string specifier does not crash", async () => {
+  await using proc = Bun.spawn({
+    cmd: [
+      bunExe(),
+      "-e",
+      `
+      const { mock } = require("bun:test");
+      try {
+        mock.module(Intl.Segmenter, () => ({ default: 1 }));
+      } catch (e) {
+        // Expected to throw - we just need it not to crash
+      }
+      console.log("ok");
+    `,
+    ],
+    env: bunEnv,
+    stdout: "pipe",
+    stderr: "pipe",
+  });
+
+  const [stdout, stderr, exitCode] = await Promise.all([proc.stdout.text(), proc.stderr.text(), proc.exited]);
+
+  expect(stdout).toContain("ok");
+  expect(exitCode).toBe(0);
+});