When upgrading SPFx projects from one version to another, when you need to upgrade one or more npm packages, often you end up with a bunch of TS errors about duplicate incompatible types. I found out, that running npm dedupe after upgrading packages, solves this issue and prevents you from having to delete node_modules and the lock file. Should we consider adding npm dedupe to the set of upgrade instructions whenever we suggested upgrading one or more packages?

/cc: @baywet @wobba @VelinGeorgiev