npm, webpack and node js core modules building

I'm trying to rebuild the swagger ui project (https://github.com/swagger-api/swagger-ui), but when I'm in the folder and run the npm run build command, it return me these errors:

ERROR in ./~/coap/index.js Module not found: Error: Cannot resolve module 'net' in /home/sibo/Scrivania/swagger-ui-master/node_modules/coap @ ./~/coap/index.js 13:22-36

ERROR in ./~/coap/lib/server.js Module not found: Error: Cannot resolve module 'net' in /home/sibo/Scrivania/swagger-ui-master/node_modules/coap/lib @ ./~/coap/lib/server.js 13:22-36

ERROR in ./~/coap/lib/agent.js Module not found: Error: Cannot resolve module 'dgram' in /home/sibo/Scrivania/swagger-ui-master/node_modules/coap/lib @ ./~/coap/lib/agent.js 12:22-38

ERROR in ./~/coap/lib/server.js Module not found: Error: Cannot resolve module 'dgram' in /home/sibo/Scrivania/swagger-ui-master/node_modules/coap/lib @ ./~/coap/lib/server.js 11:22-38

Looking over the internet I understand that the problems are the nodejs modules, someone can help me to solve the problem?

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