The sfdx plugin system doesn't seem to be working correctly, confirmed by a colleague.

When trying to run the default hello:org command this is the error produced:

src/commands/hello/org.ts(11,22): error TS2417: Class static side 'typeof Org' incorrectly extends base class static side 'typeof SfdxCommand'.
 Types of property 'flagsConfig' are incompatible.
   Type '{ name: IOptionFlag<string>; force: IBooleanFlag<boolean>; }' is not assignable to type 'SfdxFlagsConfig'.
     Property 'name' is incompatible with index signature.
       Type 'IOptionFlag<string>' is not assignable to type 'string | boolean | IBooleanFlag<any> | JsonMap | IOptionFlag<any>'.
         Type 'IOptionFlag<string>' is not assignable to type 'IOptionFlag<any>'.
           Type 'IOptionFlag<string>' is not assignable to type '{ completion?: ICompletion; }'.
             Types of property 'completion' are incompatible.
               Type 'ICompletion' is not assignable to type 'ICompletion'. Two different types with this name exist, but they are unrelated.
                 Types of property 'cacheKey' are incompatible.
                   Type '(ctx: ICompletionContext) => Promise<string>' is not assignable to type '(ctx: ICompletionContext) => Promise<string>'. Two different types with this name exist, but they are unrelated.
                     Types of parameters 'ctx' and 'ctx' are incompatible.
                       Type 'ICompletionContext' is not assignable to type 'ICompletionContext'. Two different types with this name exist, but they are unrelated.
                         Types of property 'config' are incompatible.
                           Type 'IConfig' is not assignable to type 'IConfig'. Two different types with this name exist, but they are unrelated.
                             Property 'channel' is missing in type 'IConfig'.
error Command failed with exit code 2.