Issue Hunting

[erhant]

• Fixes #17 by adding docs about this case, no need for more countermeasures for this as it is a reaaaallly edge case & doesnt really matter outside a serverless setting.

• Fixes #16

• Fixes #6 by adding checks within batch and addSignal functions.

• Fixes #10 by using Parcel with much better settings (w.r.t readability of errors thrown from the bundled code)

• Fixes #13 by returning the following type instead of just a boolean (for success):

{
    success: boolean, // whether the operation was succesfull
    destination: string, // name of next state (after signal)
    source: string, // name of current state (before signal)
    batchType: string, // batch type for the current state
    params: any, // params for the current  state
  };

more coming soon.