Replace express-graphql with GraphQL Helix middleware

[koistya]

• Replace express-graphql (poorly maintained) with GraphQL Helix middleware
• Update GraphQL middleware in api/graphql.ts
• Move GraphQL schema object from api/graphql.ts to api/schema.ts
• Update project dependencies to the latest versions
• Convert yarn setup script from CommonJS to ESM

import express from "express";
import {
  getGraphQLParameters,
  processRequest,
  renderGraphiQL,
  sendResult,
  shouldRenderGraphiQL,
} from "graphql-helix";
import { Context } from "./context";

// GraphQL API middleware
app.use("/api", express.json(), async function api(req, res, next) {
  try {
    if (shouldRenderGraphiQL(req)) {
      res.send(renderGraphiQL({ endpoint: "/api" }));
    } else {
      const params = getGraphQLParameters(req);
      const result = await processRequest<Context>({
        operationName: params.operationName,
        query: params.query,
        variables: params.variables,
        request: req,
        schema,
        contextFactory: () => new Context(req),
      });

      sendResult(result, res, (result) => ({
        data: result.data,
        errors: result.errors?.map((err) => {
          // Report errors except for user input validation errors
          if (!(err.originalError instanceof ValidationError)) {
            reportError(err, req, params);
          }
          return err;
        }),
      }));
    }
  } catch (err) {
    next(err);
  }
}

Ref graphql/express-graphql#797