Unused var warnings

[probins]

Just ran uglifyjs on https://unpkg.com/system-register-loader@0.3.1/dist/system-register-loader.js and get 2 warnings:
WARN: Dropping unused variable thisLoader [system-register-loader.js:1198,8]
WARN: Side effects in initialization of unused variable PROCESS_REGISTER_CONTEXT [system-register-loader.js:1196,6]

These are both in https://github.com/ModuleLoader/system-register-loader/blob/master/src/system-register-loader.js and are indeed not used.