Do you have Java installed? Check you have Apple's older Java 1.6 installed.
You could try one of the snapshots here. But to answer your question, no there's no newer version other than the snapshots listed.

I have a suspicion the problem might be the Phex app found in the MacOS folder of the Phex package. This was an issue a few years ago. You could try replacing the stub file with this one here called JavaApplicationStubMavericks. Unzip, copy the JavaApplicationStub file into the
phex_3.4.2.x/Phex.app/Contents/MacOS folder & replace the one that's there. ie: find the Phex program package & right-click / control-click to open the package. Then open each folder until you find the MacOS folder & open this. You will find a stub file of same name.
If this still doesn't fix the issue, check you have the older Apple Java 1.6 installed on your system. The newer Oracle Java uses a different system & I don't believe Phex will run with it due to Phex only referencing the older Apple Java positioning on OSX file system.

Apple often change the web page url of older files so if you need the discontinued Apple Java, see here for a 3rd party file-hosting site option.