How to resolve error TS2339: Property 'xxx' does not exist on type 'yyy'?

Question

typescript

There is a class:

export default class BaseModel {
  _: {} = {}

  constructor (options: OptionsInterface) {
    const { model, aliases } = options

    Object.keys(aliases).forEach(key => {
      const alias = aliases[key]
      this._[alias] = model[key]
    })
  }
}

And every mention of the _ property of this class gives the following error:

TS2339: Property '_' does not exist on type 'BaseModel'

I restart the assembly, the error disappears, I make a change - the error gets out.

I explicitly declare a property, I give it a type and a default value, but what does it give me that this property is not in the class?
And why can't I assign a lowercase type object(error: ESLint: 'object' is not defined.(no-undef))?
I'm going bald soon, cuckoo rides from this typescript

Answer 1

https://www.typescriptlang.org/play?#code/C4TwDgpg...