Reject invalid directives on scalars in 15.0.0 #893

Since #864, scalars get the directives from the schema. When one of them is undeclared or has an argument its definition doesn't have, tools logs Scalar 'Date' is built without its directives from the schema: … and builds the scalar without them, because those scalars always built before. Every other type throws a SchemaError for the same mistake.

What to change

• throw the SchemaError in SchemaParser#createScalar instead of logging it
• turn DirectiveTest.should warn about undeclared directives on scalars and build them without the schema's directives into a test for the error
• mention it in the 15.0.0 release notes