fix(eval): vite-node-specific defense against the server-close race that throws ERR_CLOSED_SERVER

[Hiroki Osame (privatenumber)]

Problem

bt eval --runner vite-node <file>.ts fails with error: eval runner exited with status exit status: 1 for projects whose Vite config enables dev.recoverable for SSR (Vite wrappers like vite-plus do by default). Invoking the cached eval-runner directly surfaces the real error: ERR_CLOSED_SERVER from vite's transformRequest.

vite-node's CLI does await runner.executeFile(file); await server.close(); (cli.ts:146-152). executeFile resolves the moment vite-node's async wrapper around the entry returns, which is immediately if the entry uses fire-and-forget. The eval-runner used main().catch(...) at the top level, so vite-node tore down the dev server while main() was still resolving await import() calls.

Same bug class as vitejs/vite#13786. The pattern has been latent since vite-node support landed; it surfaces now because configs that re-enable dev.recoverable reopen the closed-server guard that #13787 silenced for SSR by default.

tests/evals/js/eval-vite-node-server-close-race/ reproduces it deterministically.

Changes

Only vite-node's CLI needs top-level await; every other runner (tsx, bun, deno, ts-node, plain Node) has event-loop semantics where fire-and-forget is the natural pattern. The runner is split to reflect that:

• scripts/eval-runner-impl.ts — shared impl. Exports main().
• scripts/eval-runner.mts — vite-node entry: imports main and awaits it. .mts forces ESM at the loader for tsx/Bun/Deno; vite-node is format-agnostic.
• Default .ts entry generated by js_runner_default_source(): impl body with main().catch(...) appended. Standalone (no import) to avoid a Deno-vs-ts-node .ts-extension conflict.
• src/eval.rs — js_runner_path_for_kind swaps the runner script to .mts only for RunnerKind::ViteNode.
• Unit tests pin the entry shapes so the fire-and-forget vs TLA asymmetry can't silently drift.