To find which files are erroring, addconsole.error('json error in file', path.join(coreLanguagesPath, lang, namespace + '.json'));
Before each of the following lines of the linked file:
TL; DR: upgrade to node Js version
v0.10.41 (Maintenance), v0.12.9 (LTS), v4.2.3 "Argon" (LTS) or v5.1.1 (Stable), depending on which major.minor version you're running.
Nodejs updates have recently been released to address a DOS vulnerability in 0.12.x to 5.x, as well as an OpenSSL vulnerability in all versions: https://nodejs.org/en/blog/vulnerability/december-2015-security-releases/