Fix schema typeMap damaging on directiveMap generation

[no1seman]

Remove forcing defaultValue on directiveMap generation because it leads to adding redundant defaultValue field to Scalars itself into typeMap:

{
    "typeMap": {
        "Int": {
            "defaultValue": 1, <- ERROR
            "parseLiteral": "function: 0x415a8fe8",
            "__type": "Scalar",
            "nonNull": {},
            "serialize": "function: 0x415a8ed8",
            "isValueOfTheType": "function: 0x415a8e98",
            "name": "Int",
            "description": "..."
        }
    }
}

Here is a simple test (without this fix it fails):

function g.test_arguments_default_values_bug()
    local function callback(_, _)
        return nil
    end

    local mutation_schema = {
        ['test_mutation'] = {
            kind = types.string.nonNull,
            arguments = {
                object_arg = {
                    kind = types.inputObject({
                        name = 'test_input_object',
                        fields = {
                            nested = {
                                kind = types.string,
                                defaultValue = 'default Value',
                            },
                        },
                        kind = types.string,
                    }),
                },
                mutation_arg = {
                    kind = types.int,
                    defaultValue = 1,
                },

            },
            resolve = callback,
        }
    }

    local directives = {
        types.directive({
            schema = schema,
            name = 'timeout',
            arguments = {
                seconds = {
                    kind = types.int,
                    description = 'Request timeout (in seconds). Default: 1 second',
                    defaultValue = 1,
                },
            },
            onField = true,
        })
    }

    local root = {
        query = types.object({
            name = 'Query',
            fields = {},
        }),
        mutation = types.object({
            name = 'Mutation',
            fields = mutation_schema or {},
        }),
        directives = directives,
    }

    local compiled_schema = schema.create(root, test_schema_name)


    t.assert_equals(compiled_schema.typeMap['Int'].defaultValue, nil)
end

[DifferentialOrange]

I think you should add the test into the code.

Does this fix change any directiveMap behavior?

[no1seman]

I think you should add the test into the code.

Test added

Does this fix change any directiveMap behavior?

Rather no than yes. It's a potential possibility to set defaultValue for inputObject by setting it in argument map but in this case one should use map and finally, after schema generation defaults must be injected to each argument of inputObject. I don't think that it's really will be needed for anyone. It is worth adding that it never worked in this implementation.

[Totktonada]

NB: Start to collect points like 'one may expect that X works in [particular way], but that would be a misbelief'.

[no1seman]

?

[Totktonada]

LGTM.