Mystery error thrown with no reference to query or operation

[adamreisnz]

Do you want to request a feature or report a bug?
Bug, but possibly caused by user error/invalid input

What is the current behavior?
This error is thrown, but the stack trace doesn't tell me where in the app it's thrown from, so I have no clues to go on:

TypeError: Cannot read properties of undefined (reading 'toArray')
  File "node_modules/mongoose/lib/query.js", line 2148, col 21, in null.<anonymous>
  File "node_modules/mongoose/lib/drivers/node-mongodb-native/collection.js", line 223, col 9, in NativeCollection.<computed> [as find]
  File "node_modules/mongoose/lib/query.js", line 2143, col 31, in model.Query.<anonymous>
  File "node_modules/mongoose/lib/helpers/query/wrapThunk.js", line 27, col 8, in model.Query._wrappedThunk [as _find]
  File "node_modules/kareem/index.js", line 370, col 33, in null.<anonymous>
  File "node:internal/process/task_queues", line 78, col 11, in processTicksAndRejections
  File "node_modules/mongoose/lib/helpers/promiseOrCallback.js", line 31, col 10, in promiseOrCallback
  File "node_modules/mongoose/lib/query.js", line 4556, col 10, in model.Query.exec
  File "node_modules/mongoose/lib/query.js", line 4639, col 15, in model.Query.Query.then

If the current behavior is a bug, please provide the steps to reproduce.
Unknown

What is the expected behavior?
Maybe this error should be handled internally in Mongoose to clarify what exactly is going wrong, as to provide a hint to the developers to indicate what query/operation is causing it to fail.

What are the versions of Node.js, Mongoose and MongoDB you are using? Note that "latest" is not a version.

• MongoDB shell version v5.0.2
• Node 16.3.0
• Mongoose 6.0.7

[IslandRhythms]

Can you provide the code you are running that is throwing this error?

[adamreisnz]

No I can't, because it's reported by Sentry and lacks any identifiable source or hint. If I could, I would have posted it here :) We use it mongoose in about 10,000 places in the app, so needle in a haystack.

…

On Thu, 7 Oct 2021, 03:33 Daniel Diaz, ***@***.***> wrote: Can you provide the code you are running that is throwing this error? — You are receiving this because you authored the thread. Reply to this email directly, view it on GitHub <#10845 (comment)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AADXYQVZRSAOYZVT3IDJLFDUFRM4NANCNFSM5FMR7D5Q> . Triage notifications on the go with GitHub Mobile for iOS <https://apps.apple.com/app/apple-store/id1477376905?ct=notification-email&mt=8&pt=524675> or Android <https://play.google.com/store/apps/details?id=com.github.android&referrer=utm_campaign%3Dnotification-email%26utm_medium%3Demail%26utm_source%3Dgithub>.

[adamreisnz]

Can you give me an indication of how/ why this happened?error might trigger? That could point me in the right direction

…

On Thu, 7 Oct 2021, 08:13 Adam Reis, ***@***.***> wrote: No I can't, because it's reported by Sentry and lacks any identifiable source or hint. If I could, I would have posted it here :) We use it mongoose in about 10,000 places in the app, so needle in a haystack. On Thu, 7 Oct 2021, 03:33 Daniel Diaz, ***@***.***> wrote: > Can you provide the code you are running that is throwing this error? > > — > You are receiving this because you authored the thread. > Reply to this email directly, view it on GitHub > <#10845 (comment)>, > or unsubscribe > <https://github.com/notifications/unsubscribe-auth/AADXYQVZRSAOYZVT3IDJLFDUFRM4NANCNFSM5FMR7D5Q> > . > Triage notifications on the go with GitHub Mobile for iOS > <https://apps.apple.com/app/apple-store/id1477376905?ct=notification-email&mt=8&pt=524675> > or Android > <https://play.google.com/store/apps/details?id=com.github.android&referrer=utm_campaign%3Dnotification-email%26utm_medium%3Demail%26utm_source%3Dgithub>. > >

[vkarpov15]

Random side note: I've never seen this particular error "Cannot read properties of undefined". Normally it would be "Cannot read property 'toArray' of undefined". Do you know why this error message is different on your end?

[adamreisnz]

@vkarpov15 thanks for fixing, is there something we can do on our end to figure out where this was thrown from (other than using .exec() everywhere)?

I know, we started seeing these errors formatted in this different manner recently as well. I suspect they may have changed the wording for these errors in a recent javascript engine update, as they started creeping up in Node 16 as well as newer browser versions.

For example, the following error changed from:

Cannot read property 'document' of null

to:

Cannot read properties of null (reading 'document')

🤷🏼

[vkarpov15]

@adamreisnz I don't think so, the find() call is swallowing the error message. My best guess would be something along the lines of calling find() before mongoose.connect(), because there are very few cases where find() should throw an error.

[adamreisnz]

Ok, would a possible scenario be if .find() is called when mongo has lost connection?
I will update to the latest Mongoose version later on and see if we can surface the actual error. Thanks.

[IslandRhythms]

would a possible scenario be if .find() is called when mongo has lost connection?

@adamreisnz try adding event handlers and see the execution order https://mongoosejs.com/docs/connections.html#connection-events

[vkarpov15]

@adamreisnz I think it is possible this error was caused by Mongoose being disconnected for more than serverSelectionTimeoutMS