After updating Angular 5 to 6, I am facing this issue while doing "ng serve".Please let me know why this error is coming.Any help would be appreciated.What could be the possible solution for this.
TypeError: Class extends value undefined is not a constructor or null
at Object.<anonymous> (ui5/node_modules/mini-css-extract-plugin/dist/CssModule.js:20:42)
at Module._compile (internal/modules/cjs/loader.js:1118:30)
at Object.Module._extensions..js (internal/modules/cjs/loader.js:1138:10)
at Module.load (internal/modules/cjs/loader.js:982:32)
at Function.Module._load (internal/modules/cjs/loader.js:875:14)
at Module.require (internal/modules/cjs/loader.js:1022:19)
at require (internal/modules/cjs/helpers.js:72:18)
at Object.<anonymous> (/home/sstproduser1/sstui5/node_modules/mini-css-extract-plugin/dist/CssModuleFactory.js:8:41)
at Module._compile (internal/modules/cjs/loader.js:1118:30)
at Object.Module._extensions..js (internal/modules/cjs/loader.js:1138:10)
at Module.load (internal/modules/cjs/loader.js:982:32)
at Function.Module._load (internal/modules/cjs/loader.js:875:14)
at Module.require (internal/modules/cjs/loader.js:1022:19)
at require (internal/modules/cjs/helpers.js:72:18)
at Object.<anonymous> (/home/sstproduser1/sstui5/node_modules/mini-css-extract-plugin/dist/index.js:12:48)