Cannot find name 'Omit' in Typescript

try using "skipLibCheck": true as one of compilerOptions in your tsconfig.json file

Omit was only recently added in TS 3.5.1 so you may be using an older version of TS in your workspace that does not support it yet.

Make sure your VS Code workspace is using the same version of TypeScript you are compiling with by following these instructions. Just open a TS file run the Select TypeScript Version command in VS Code, and opt to use your workspace version of TypeScript (which should be 3.5.1)