A query such as:

query {
  requiredArgs(count: x) {
    scalar
    complexScalar
  }
  nonNullItem {
    scalar
    complexScalar
    variableScalar(count: 10)
  }
}

results in complexityMap, being undefined, and the error TypeError: Cannot convert undefined or null to object arising from this call.

Here's a reproduction https://github.com/dburles/graphql-query-complexity/blob/bug/src/__tests__/QueryComplexity-test.ts#L800-L821. Running this test will result in the error being thrown.

GraphQL should be reporting "Argument \"count\" has invalid value x.".