Ambiguous behavior for type nullability mismatch between variables and arguments

[DifferentialOrange]

GraphQL spec (October 2021) states that

IsVariableUsageAllowed(variableDefinition, variableUsage)

• Let variableType be the expected type of variableDefinition.
• Let locationType be the expected type of the Argument, ObjectField, or ListValue entry where variableUsage is located.

AreTypesCompatible(variableType, locationType)

• If locationType is a non-null type:
  • If variableType is NOT a non-null type, return false.

I build a simple node application with graphql 15.4.0.

var { graphql, buildSchema } = require('graphql');

var rootValue = {
  test: (args) => {
    return args;
  },
}

function PrintResponse(response) {
  if (response.hasOwnProperty('data')) {
    console.log(JSON.parse(JSON.stringify(response.data)))
  }

  if (response.hasOwnProperty('errors')) {
    console.log(JSON.parse(JSON.stringify(response.errors)))
  }
}

var schema = buildSchema(`
  type result {
    arg1: Float!
  }

  type Query {
    test(arg1: Float!): result
  }
`)

Calling this query results in error.

var query1 = `query MyQuery($var1: Float = null)  { test(arg1: $var1)  { arg1 } }`

graphql({
  schema,
  source: query1,
  rootValue,
  variableValues: { var1: 1.12}
}).then(PrintResponse)

[ { message:
     'Variable "$var1" of type "Float" used in position expecting type "Float!".',
    locations: [ [Object], [Object] ] } ]

Calling this query results in success.

var query2 = `query MyQuery($var1: Float = 0)  { test(arg1: $var1)  { arg1 } }`

graphql({
  schema,
  source: query2,
  rootValue,
  variableValues: { var1: 1.12}
}).then(PrintResponse)

{ test: { arg1: 1.12 } }

The only difference is default value -- types are the same. Based on specification, it is expected to get an error in the second case too.

[DifferentialOrange]

Well, it seems that I've missed some points in specification.

IsVariableUsageAllowed(variableDefinition, variableUsage)

• If locationType is a non-null type AND variableType is NOT a non-null type:
  • Let hasNonNullVariableDefaultValue be true if a default value exists for variableDefinition and is not the value null.
  • If hasNonNullVariableDefaultValue is NOT true AND hasLocationDefaultValue is NOT true, return false.
  • Let nullableLocationType be the unwrapped nullable type of locationType.
  • Return AreTypesCompatible(variableType, nullableLocationType).