src: don't include a null character in the WriteConsoleW call

Fixes: https://github.com/nodejs/node/issues/7755
PR-URL: https://github.com/nodejs/node/pull/7764
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Ben Noordhuis <info@bnoordhuis.nl>

src/node.cc

@@ -257,7 +257,10 @@ static void PrintErrorString(const char* format, ...) {
 
   std::vector<wchar_t> wbuf(n);
   MultiByteToWideChar(CP_UTF8, 0, out.data(), -1, wbuf.data(), n);
-  WriteConsoleW(stderr_handle, wbuf.data(), n, nullptr, nullptr);
+
+  // Don't include the null character in the output
+  CHECK_GT(n, 0);
+  WriteConsoleW(stderr_handle, wbuf.data(), n - 1, nullptr, nullptr);
 #else
   vfprintf(stderr, format, ap);
 #endif