During minification of JS code, readed from the file '/Content/Assets/BasicMapWidget/basic-map-widget.js', by Closure Remote JS minifier error has occurred.
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When accessing to the Google Closure Compiler Service API occurred error with HTTP status code 'MethodNotAllowed'.
Don't use the Closure Compiler service for real things. It is only really a toy (intended for experimentation). The compiler version is changed without warning, has no uptime guarantees, and is throttled in many ways (including globally: it will just shut down if the load is to high).
Use the version from npm version. Modern releases use Oracle's native image tool to avoid the Java dependency and get quick start up.