Have you made any modifications to the source in lib/ in your project? If you have, and you did not remove the entries from project.properties the cloud compile will upload the changed versions then ignore them and use the version in the cloud compile.
Actually, it's not a bad idea to change the lines in project.properties that look sort of like this:
dependencies.neopixel=1.0.1
dependencies.JsonParserGeneratorRK=0.1.5
instead to:
orig_dependencies.neopixel=1.0.1
orig_dependencies.JsonParserGeneratorRK=0.1.5
This will force cloud and local compile to both use the same version that you have in your lib directory.
You may also want to delete the lib/JsonParserGeneratorRK/test directory. That shouldn't have been in the uploaded library.
The other situation is that there is a time limit for how long a cloud compile can take. It's a few minutes. If the compile takes too long it terminates and does not always return a reasonable error.
The other thing you can try is invoking the cloud compile from a terminal window and see if it returns a better error. Use Particle: Launch CLI from the command palette then from the terminal window:
particle compile argon . --target 5.1.0