BUG: malformed includes raises NoMethodError

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• Problem/bug report.
• Feature request.
• Request for support. Note: Please try to avoid submitting issues for support requests. Use Gitter instead.

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• I've searched for an existing issue.
• I've asked my question on Gitter and have not received a satisfactory answer.
• I've included a complete bug report template. This step helps us and allows us to see the bug without trying to reproduce the problem from your description. It helps you because you will frequently detect if it's a problem specific to your project.
• The feature I'm asking for is compliant with the JSON:API spec.

Description

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Bug reports:

The CSV gem raises a NoMethodError when passed an array

e.g. CSV.parse_line(["memberships"]) raises

private method `gets' called for ["memberships"]:Array

And JR in 0.9.x and 0.10.x in a few places uses CSV.parse_line but only rescues CSV::MalformedCSVError

making a request like v1/users/:id?include[]=memberships with call e.g. JSONAPI::RequestParser#parse_include_directives with ["memberships"] and raise an unhandled error.

My proposal is 1) encapsulate wherever CSV.parse_line is called and 2) ensure any errors are handled and raises as JSONAPI::Exceptions

I could possibly make PRs to 0.9 and 0.10

(We're still on 0.9 due to bugs changes in handling of polymorphic types and plain old resources, but I'd like to help however I can)

Start at JSONAPI::RequestParser#parse_include_directives and trace the places where CSV.parse_line is called in the 0.9 and 0.10 code paths. Reproduce the array input from include[]=memberships, then verify malformed input no longer raises an unhandled NoMethodError and is surfaced as a JSONAPI::Exceptions error.