TypeError: Cannot read property 'collections' of null

[chuongle]

Today I encountered a weird issue with LokiJS. For whatever reason, the main db file (metadata) got wiped, the file is still there but the content is empty. So when the application started again, I got the TypeError: Cannot read property 'collections' of null error. The issue is I can catch any of these error. The only reason I am aware of this error is because I have sentry setup and it automatically caught it.

Here is the code I use:

try {
  const db = new Loki('test.db', {
    adapter: new LokiFsStructuredAdapter(),
    autosave: true,
    autosaveInterval: 5000
  });

  db.loadDatabase({}, (error) => {
    if (error) {
      console.log('fail to load error: ', error);
    } else {
      console.log('successfully load db')
      // set up collections and insert data
    }
  });  
} catch (error)
  console.log('error', error);
}

Here is the full error:

TypeError: Cannot read property 'collections' of null
    at Interface.eval (webpack:///./node_modules/lokijs/src/loki-fs-structured-adapter.js?:153:31)
    at Interface.emit (events.js:327:22)
    at Interface.EventEmitter.emit (domain.js:467:12)
    at Interface.close (readline.js:424:8)
    at ReadStream.onend (readline.js:202:10)
    at ReadStream.emit (events.js:327:22)
    at ReadStream.EventEmitter.emit (domain.js:467:12)
    at endReadableNT (internal/streams/readable.js:1327:12)
    at processTicksAndRejections (internal/process/task_queues.js:80:21)

I am not sure what is going on here. Is there a right way of handling error that I am missing?

[stale[bot]]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions.

[Losses]

One case may trigger this problem: you are creating a collection but didn't write anything into it, this is a bug of the loki-fs-structured-adapter and we are trying to fix it.

[Losses]

BTW, there's a fixed version of the adapter, but it was refactored with TypeScript.

https://github.com/recative/studio/blob/main/packages/loki-fs-structured-adapter/main.ts

[chuongle]

@Losses Thank you for the update!!!