if package can't be found, we need to throw an error

[ORESoftware]

with this setup:

  "searchRoots": [
    "/home/oleg/WebstormProjects/oresoftware/r2g",
    "/home/oleg/WebstormProjects/sumanjs/suman",
    "/home/oleg/WebstormProjects/sumanjs/suman-types",
    "/home/oleg/WebstormProjects/sumanjs/suman-watch"
  ],
  "packages": {
    "@oresoftware/r2g": true,
    "suman": true,
    "suman-types": true,
    "suman-watch": true
  }

"@oresoftware/r2g" won't be found, because the package name was refactored to just "r2g", so we need to throw an error in that case.