assert package manager is allocated once before use

[robobun]

:x: @pfgithub, your commit 295cdc6fa92be057851903f19fc6f1405f75b88a has 11 failures in #6410:

test/integration/next-pages/test/dev-server.test.ts - 1 failing on 🐧 3.20 x64-baseline

test/integration/next-pages/test/dev-server.test.ts - 1 failing on 🐧 3.20 x64

test/v8/v8.test.ts - 22 failing on 🐧 3.20 aarch64

test/v8/v8.test.ts - 22 failing on 🐧 3.20 x64-baseline

test/v8/v8.test.ts - 22 failing on 🐧 3.20 x64

test/js/node/test/parallel/fs-watch-recursive-linux-parallel-remove.test.js - 1 failing on 🐧 3.20 aarch64

test/js/node/test/parallel/fs-watch-recursive-linux-parallel-remove.test.js - 1 failing on 🐧 3.20 x64-baseline

test/js/node/test/parallel/fs-watch-recursive-linux-parallel-remove.test.js - 1 failing on 🐧 3.20 x64

test/js/bun/ffi/cc.test.ts - 1 failing on 🐧 3.20 aarch64

test/js/bun/ffi/cc.test.ts - 1 failing on 🐧 3.20 x64-baseline

test/js/bun/ffi/cc.test.ts - 1 failing on 🐧 3.20 x64

test/js/node/child_process/child_process.test.ts - 1 failing on 🐧 3.20 aarch64

test/js/node/child_process/child_process.test.ts - 1 failing on 🐧 3.20 x64-baseline

test/js/node/child_process/child_process.test.ts - 1 failing on 🐧 3.20 x64

test/cli/install/bun-link.test.ts - 4 failing on 🐧 3.20 aarch64

test/cli/install/bun-link.test.ts - 4 failing on 🐧 3.20 x64-baseline

test/cli/install/bun-link.test.ts - 4 failing on 🐧 3.20 x64

test/js/web/fetch/fetch.tls.test.ts - 1 failing on 🍎 14 aarch64

test/js/node/test/parallel/http2-pipe.test.js - code 1 on 🍎 13 aarch64

test/js/bun/http/serve.test.ts - 1 failing on 🍎 13 aarch64

test/js/bun/http/serve.test.ts - segmentation fault on 🐧 3.20 aarch64

test/js/bun/http/serve.test.ts - segmentation fault on 🐧 3.20 x64-baseline

test/js/bun/http/serve.test.ts - 1 failing on 🍎 13 x64

test/js/bun/http/serve.test.ts - segmentation fault on 🐧 3.20 x64

test/cli/hot/hot.test.ts - timeout on 🪟 2019 x64

test/cli/run/require-cache.test.ts - 1 failing on 🪟 2019 x64-baseline