eslint for array access

I have a problem that I think can be boiled down to this code snippet

public a() {
    return {a: 0};
}

public b() {
    return this.a()[0];
}

A while back the a function returned an array, but got refactored into returning a single object. It would have been great if I got an error on the b function, but as it stands right now it compiles happily and results in errors at runtime.

So even though I understand why it is valid code (accessing the zero key on the a object), I would like to have eslint or tsc warn me. But I have a hard time finding any rules/config that matches that. So is it at all possible?

Can add that this is the compilerOptions of my tsconfig

  "compilerOptions": {
    "skipLibCheck": true,
    "strict": true,
    "strictNullChecks": false,
    "typeRoots": ["./node_modules/@types", "./Script/typings"],
    "experimentalDecorators": true,
    "useDefineForClassFields": false,
    "esModuleInterop": true,
    "noImplicitAny": false,
    "module": "ES2020",
    "target": "ES2020",
    "lib": [
      "ES2021",
      "ES6",
      "DOM",
      "DOM.Iterable"
    ],
    "allowJs": false,
    "sourceMap": true,
    "moduleResolution": "node",
    "paths": {
      "/": [
        "./"
      ],
      "/*": [
        "./*"
      ]
    },
    "outDir": "build"
  }