fix: preserve child process signal exit codes (#113685)

Co-authored-by: Peter Steinberger <steipete@golden-gate.local>

src/cli/subprocess-exit-code.ts

@@ -0,0 +1,12 @@
+import { constants as osConstants } from "node:os";
+
+export function resolveSubprocessExitCode(
+  exitCode: number | null | undefined,
+  signal: NodeJS.Signals | null | undefined,
+): number {
+  if (typeof exitCode === "number") {
+    return exitCode;
+  }
+  const signalNumber = signal ? (osConstants.signals as Record<string, number>)[signal] : undefined;
+  return typeof signalNumber === "number" ? 128 + signalNumber : 1;
+}