Schema directive visitor in federated schema broken in 5.x

[tlivings]

Previously, applying:

SchemaDirectiveVisitor.visitSchemaDirectives(federatedSchema, schemaDirectives);

Would allow custom directives to be applied to a federated schema.

In 5.0, this fails with an exception:

TypeError: Cannot read property 'concat' of undefined

Due to this line:

directiveNodes = directiveNodes.concat(extensionASTNode.directives);

In this case, directiveNodes is undefined because for the Extension type, type.astNode is not undefined but type.astNode.directives is.

[yaacovCR]

#1490 references this issue in error, fix should be in #1506

[yaacovCR]

Not sure if you are ready for this yet, but you should be able to test fix with new separate graphql-tools packages:

@graphql-tools/schema
@graphql-tools/utils

via canary tag. Would be extremely helpful to us!

Example project using new scoped packages: https://github.com/yaacovCR/apollo-stitcher/blob/master/package.json

v6 API in progress: https://www.graphql-tools.com/docs/introduction

[yaacovCR]

Closed by #1419.