Skip complexity calculation by directiveEstimator when astNode is undefined

[hnq90]

Currently, I'm using Apollo Server 2 with Federation.

In QueryComplexity.ts, I found that field in estimatorArgs could have undefined value in astNode property.

And if we use DirectiveEstimator, args.field.astNode in this line could be undefined and make getDirectiveValues throws error.

So it's better to set default value of field.astNode to an empty object {}.

These are which I printed from field:

_entities:
{ description: '',
    type: [_Entity]!,
    args: [ [Object] ],
    resolve: [Function],
    subscribe: undefined,
    deprecationReason: undefined,
    extensions: undefined,
    astNode: undefined,
    name: '_entities',
    isDeprecated: false,
    [Symbol()]: true },

_service:
{ description: undefined,
    type: _Service!,
    args: [],
    resolve: [Function],
    subscribe: undefined,
    deprecationReason: undefined,
    extensions: undefined,
    astNode: undefined,
    name: '_service',
    isDeprecated: false,
    [Symbol()]: true },

Update: Skip complexity calculation by directiveEstimator when astNode is undefined

[ivome]

Would you mind adding a simple test case to prevent regression in the future?

[ivome]

This is published with v0.4.1. Thanks for the PR @hnq90

[hnq90]

@ivome Thank you. 👍