[strict-boolean-expressions] ignoreRhs is too lenient

[OliverJAsh]

Repro

{
  "rules": {
    "@typescript-eslint/strict-boolean-expressions": [
      2,
      {
        "ignoreRhs": true,
        "allowNullable": true
      }
    ]
  }
}

{
  declare const myString: string;
  declare const myBoolean: boolean;
  const expression = myBoolean && myString; // Expect: no error (thanks to `ignoreRhs`)
  if (expression) {} // Expect: error
}

{
  declare const myString: string;
  declare const myBoolean: boolean;
  if (myBoolean && myString) {} // Expect: error. Actual: no error. ❌
}

Additional Info

This does error as expected in TSLint (with the equivalent rule of the same name).

In the first example, the right-hand side of expression will not be coerced (until it's later used in an if statement), so it's safe to for it to be a non-boolean type.

In the second example however, the right-hand side of the condition in the if statement will be coerced, so it's not safe for it to be a non-boolean type.

Versions

package	version
@typescript-eslint/eslint-plugin	2.4.0
@typescript-eslint/parser	2.4.0
TypeScript	3.6.4
ESLint	6.5.1
node	12.8.1
npm	6.10.2