test: refactor test-child-process-send-type-error.js

* Add exit listener to child process to check return code. Previously,
  child process faiilure would not cause the test to fail.
* Use common.mustNotCall() to guarantee callback is not invoked.
* Insert blank line per test writing guide.

test/parallel/test-child-process-send-type-error.js

@@ -1,5 +1,6 @@
 'use strict';
 const common = require('../common');
+
 const assert = require('assert');
 const cp = require('child_process');
 
@@ -11,13 +12,18 @@ function fail(proc, args) {
 
 let target = process;
 
-if (process.argv[2] !== 'child')
+if (process.argv[2] !== 'child') {
   target = cp.fork(__filename, ['child']);
+  target.on('exit', common.mustCall((code, signal) => {
+    assert.strictEqual(code, 0);
+    assert.strictEqual(signal, null);
+  }));
+}
 
 fail(target, ['msg', null, null]);
 fail(target, ['msg', null, '']);
 fail(target, ['msg', null, 'foo']);
 fail(target, ['msg', null, 0]);
 fail(target, ['msg', null, NaN]);
 fail(target, ['msg', null, 1]);
-fail(target, ['msg', null, null, common.noop]);
+fail(target, ['msg', null, null, common.mustNotCall()]);