improve error a bit

Author: bartlomieju

ext/node/polyfills/process.ts

@@ -437,7 +437,7 @@ Object.defineProperty(Process.prototype, "exitCode", {
     return ProcessExitCode;
   },
   set(code: number | string | null | undefined) {
-    if (code != null) {
+    if (!!code) {
       // This is looser than `denoOs.setExitCode` which requires exit code
       // to be decimal or string of a decimal, but Node accept eg. 0x10.
       code = parseInt(code) || 0;

runtime/js/30_os.js

@@ -104,7 +104,9 @@ function getExitCode() {
 function setExitCode(value) {
   const code = NumberParseInt(value, 10) || undefined;
   if (typeof code !== "number") {
-    throw new TypeError("Exit code must be a number.");
+    throw new TypeError(
+      `Exit code must be a number, got: ${code} (${typeof code}).`,
+    );
   }
   op_set_exit_code(code);
 }

tests/node_compat/test/.tmp.318/test-stdin-from-file-spawn-cmd

@@ -0,0 +1 @@
+echo hello

tests/node_compat/test/.tmp.318/test-stdin-from-file-spawn.js

@@ -0,0 +1,16 @@
+
+'use strict';
+const { spawn } = require('child_process');
+// Reference the object to invoke the getter
+process.stdin;
+setTimeout(() => {
+  let ok = false;
+  const child = spawn(process.env.SHELL || '/bin/sh',
+    [], { stdio: ['inherit', 'pipe'] });
+  child.stdout.on('data', () => {
+    ok = true;
+  });
+  child.on('close', () => {
+    process.exit(ok ? 0 : -1);
+  });
+}, 100);