Before You File a Proposal Please Confirm You Have Done The Following...

• I have searched for related issues and found none that match my proposal.
• I have searched the current rule list and found no rules that match my proposal.
• I have read the FAQ and my problem is not listed.

My proposal is suitable for this project

• I believe my proposal would be useful to the broader TypeScript community (meaning it is not a niche proposal).

Link to the rule's documentation

https://typescript-eslint.io/rules/no-unnecessary-condition

Description

I constantly see LLMs generating code that checks variables by calling Array.isArray on them despite them being strictly typed as array. Adding logic into no-unnecessary-condition to detect these redundant calls would reduce code by avoiding unnecessary conditions and helps in reviewing AI generated code.

Fail

const items: number[] = [1, 2, 3];
if (Array.isArray(items)) {
  console.log("items is an array");
}

Pass

const items: number[] | null = [1, 2, 3];
if (Array.isArray(items)) {
  console.log("items is an array");
}

Additional Info

Maybe also include logic to detect unnecessary items instanceof Array?