UnhandledPromiseRejection while OGM initialize on Neo4j GraphQL Express Server

Question

I am using express with Neo4j graphql.

Seeing this exception without specific line indications in my code.

node:internal/process/promises:289
            triggerUncaughtException(err, true /* fromPromise */);
            ^

[UnhandledPromiseRejection: This error originated either by throwing inside of an async function without a catch block, or by rejecting a promise which was not handled with .catch(). The promise rejected with the reason "[object Array]".] {   code: 'ERR_UNHANDLED_REJECTION' }

Node.js v20.3.0

1. I have graph data models defined in "graph-data-models.js"

    ...        
    const driver = neo4j.driver(
    ...
    );
   
    const ObjectGraphMap = new OGM({ typeDefs, driver });
    const Challenge = ObjectGraphMap.model("Challenge");
    ...
   

2. Express Server on "app.js". Server should start from here. I run node app.js.

   ...
   try {
       await ObjectGraphMap.init();
       app.listen(port, () => {
           logger.info(`Data API App listening at http://localhost:${port}`);
       });
   } catch(e) {
       logger.error("OGM init failed",e);
   }
   

3. API Definitions in "api.js"

...
app = express()
...
app.get("/challenges", getChallenges);
...

4. Data Models used in "api-impl.js"

...
const getChallenges = async (req, res) => {
    try {
      ...  
      Challenge.find({
            ... }
        })
        .then((challenge) => {
           ...
        })
        .catch((err) => {
        ...
        });
    } catch (error) {
        ...
    } 
}
...

It looks to me like something more than just wrapping around a try-catch at all places. How can I debug and find out the issue? OGM init needs some change but then-catch model on "app.js" like.

...
ObjectGraphMap.init()
    .then(() => {
    ...
    }) 
    .catch(() => {
    ...
    })
...

does not cut it.

Answer 1

I figured out the issue after retracing all the steps I made. Unfortunately, it is not related to any of the details I had posted. Partly the reason it took me so long to debug.

However, it is not really the solution for it. I had added a field on schema (which is used to instantiate the driver - variable typeDefs). So, ObjectGraphMap.init() fails. Alas, Neo4j does not (yet) have the flexible schema integration with graphql. It may be not that bad as it can get pretty dynamic and error-prone without hard-fixing the schema.

PS: Stacktrace needs to improve though. Not actually accepting this as an answer because there seems to be something to address on ES. Check this out and this too.