Grafast processFragment does not permit use of string arguments

[litewarp]

Summary

The evalDirectiveArgDirect function, which is called during processFragment does not accept a StringValue as an acceptable value type and throws an error:

export function evalDirectiveArgDirect<T = unknown>(
  directive: DirectiveNode,
  argumentName: string,
  variableValuesStep: __TrackedValueStep,
  defaultValue: T,
): T | undefined {
  if (!directive.arguments) return defaultValue;
  const argument = directive.arguments.find(
    (a) => a.name.value === argumentName,
  );
  if (argument !== undefined) {
    const value = argument.value;
    switch (value.kind) {
      case "Variable": {
        return variableValuesStep.get(value.name.value).eval();
      }
      case "BooleanValue": {
        return value.value as any;
      }
      case "IntValue": {
        return parseInt(value.value, 10) as any;
      }
      case "NullValue": {
        return null as any;
      }
      // <------------------- NO STRINGS!!!!
      default: {
        throw new SafeError(
          `Unsupported @${directive.name}(${argumentName}:) argument; expected Variable, Boolean or null; but received '${value.kind}'`,
        );
      }
    }
  } else {
    return defaultValue;
  }
}

Steps to reproduce

Install the StreamDeferPlugin from graphile-build
Install graphql version 16.1.0-experimental-stream-defer.6
create dummy tables and add the @defer(label: "any string label will throw") directive to a fragment

Expected results

String values should be used.

Actual results

It errs

Additional context

{
    "dependencies": {
    "@dataplan/json": "0.0.1-beta.23",
    "@dataplan/pg": "0.0.1-beta.25",
    "@grafserv/persisted": "0.0.0-beta.26",
    "@graphile-contrib/pg-many-to-many": "2.0.0-beta.3",
    "@graphile-contrib/pg-omit-archived": "4.0.0-beta.2",
    "@graphile/operation-hooks": "^1.0.0",
    "@graphile/pg-aggregates": "0.2.0-beta.6",
    "@graphile/simplify-inflection": "8.0.0-beta.5",
    "graphile-build": "5.0.0-beta.24",
    "graphile-build-pg": "5.0.0-beta.28",
    "graphile-config": "0.0.1-beta.9",
    "graphile-export": "^0.0.2-beta.19",
    "graphql": "^16.1.0-experimental-stream-defer.6",
    "graphql-ws": "^5.16.0",
    "hono": "^4.5.1",
    "jsonwebtoken": "^9.0.2",
    "postgraphile": "5.0.0-beta.29",
    "postgraphile-plugin-connection-filter": "3.0.0-beta.3"
  },
  "devDependencies": {
    "@swc/core": "^1.6.6",
    "@swc/jest": "^0.2.36",
    "@types/express": "^4.17.21",
    "@types/jsonwebtoken": "^9.0.6",
    "@types/node": "^20.14.11",
    "bun-types": "^1.1.20",
    "jest": "^29.7.0",
    "tsup": "^8.1.2",
    "tsx": "^4.16.2",
    "typescript": "^5.5.3"
  },
}

Possible Solution

Permit String Arguments to be used(?)

Will investigate and submit a PR eventually