We have a similar problem where we have started getting the error
‘You are using version of TypeScript 2.6.2 which is not supported; supported versions >=3.2.1’.
Our package.json shows typescript version as “typescript”: “~3.2.4” so I’m not sure what the problem is. I have searched our entire project and cannot see any reference to 2.6.2.
Our build is running on an Azure DevOps hosted build agent so the TypeScript version installed there is somewhat out of our control