fix(typeMerging): can't return a list of merged types

[nicolas-cherel]

Found a tricky one. I spent several hours trying to figure out exactly what going on, It looks like transparent querying of list / object bites us hard.

Long story short, the fallback resolve of merge config doesn't handle difference between list or non list of queried items. So it goes on quering with provided query field that will just query a single object, while info.returnType is a list of object.

So handleResult(), reading the returnType will call handleList() while result is an object, and then crash on list.map

I suspect a simple negotiation of list / non list on query return type and expected return type should do the trick, but despite my efforts, I couldn't figure out where and how to put it without introducing unwanted variability in resolution logics. I have my suspicions that it'll end up in default resolver of merge config.

[nicolas-cherel]

I only enriched a test case, btw

[yaacovCR]

Thanks so much @nicolas-cherel for reporting this.

[yaacovCR]

Fixed on master, available as alpha in npm: 6.0.10-alpha-438f706.0

Quickly update your package.json by running:

npx match-version @graphql-tools 6.0.10-alpha-438f706.0

Thanks again for reporting! Please let me know if anything.

[nicolas-cherel]

Looks good on my app ! thanks @yaacovCR :)