Fix coreNode error when fetching public data with no user session

[markmhendrickson]

As first encountered with markmhendrickson/humans#12, I'm getting TypeError: Cannot read property 'coreNode' of undefined upon calling getFile and reaching: https://github.com/blockstack/blockstack.js/blob/950dc4fc838099835ce0592f245453c770663b84/src/storage/index.ts#L253

sessionData.userData is undefined and throws an error instead of getting to use caller.appConfig.coreNode

cc @zone117x since he appears to be the last person to touch this part of the code

[markmhendrickson]

@agraebe is this something the DevX team may want to take on soon?

[zone117x]

Hmm, @markmhx can you provide a repo/snippet of code to easily reproduce? Looks like this is an easy fix but not entirely sure what the intention behind this code

[markmhendrickson]

How about this as a snippet?

The intention is basically to query a user's public data using their ID without necessarily having a session oneself (e.g. for a public profile).

[hstove]

It seems like this could be fixed with a sessionData.userData?.coreNode ?

[friedger]

This breaks the todo-list tutorial to lookup public lists for new users. https://docs.blockstack.org/authentication/building-todo-app#sign-out-and-see-your-public-tasks

[markmhendrickson]

@agraebe It seems this was de-prioritized on the DevX side, correct? It seems like pretty core SDK functionality to me, so I'd suggest taking another look if we can.