Check out example codes for "ERROR in node_modules/rxjs/internal/types.d.ts(81,44): error TS1005: ';' expected.". It will help you in understanding the concepts better.

Code Example 1

This problem might arise due to version mismatch. To solve your problem you need to do following changes in your package.json file.
Go to package.json and modify "rxjs": "^6.0.0" to "rxjs": "6.0.0"
then npm update
then ng serve

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