Before You File a Bug Report Please Confirm You Have Done The Following...

• I have tried restarting my IDE and the issue persists.
• I have updated to the latest version of the packages.
• I havesearched for related issues and found none that matched my issue.
• I haveread the FAQ and my problem is not listed.

Playground Link

https://typescript-eslint.io/play/#ts=5.2.2&fileType=.ts&code=MYewdgzgLgBBIFsCmBBATmghgTxgXhgG0BYAKBhgG8YBLAEwC4YAiegeTCWYBoYpsADkibN%2BQlMxgBfbmQrV6I9px59BwlmKQBhSTLlVajFvQAqAdxCqtIrROmzyhxSboWrvG5vUAhPY-kjJTcACzQkLk91W3V7KTIAXQBuMjItGABlRCRTdXwYACUkUDQ6AB5oNBowAHNeSuqawgSAPhTSMnhkdCxsADpwugBXYCQyrORcoRaAChmkMCgqpAheGigkLA2kAEp8FqoDUEhYBToooWl89c3Mbfaj8GgYBaXcAlfliEJ6BJgAfn%2BBGa7Qon36AiGEBCMy0OweTnCUCGaDAL0WX3aMioUnhQA&eslintrc=N4KABGBEBOCuA2BTAzpAXGUEKQAIBcBPABxQGNoBLY-AWhXkoDt8B6Jge1tiacTJTIAhtEK0yHJgBNK%2BSpPRRE0aB2iRwYAL4gtQA&tsconfig=N4KABGBEDGD2C2AHAlgGwKYCcDyiAuysAdgM6QBcYoEEkJemy0eAcgK6qoDCAFutAGsylBm3TgwAXxCSgA&tokens=false

Repro Code

constsomeArray=[{id:"idOne",type:"typeA"},{id:"idOne",type:"typeC"},{id:"idTwo",type:"typeA"},{id:"idTwo",type:"typeB"},{id:"idThree",type:"typeA"}];typeSomeType=Record<string,string[]>;someArray.reduce<SomeType>((entries,iteratee)=>{const{ id, type}=iteratee;constentry=entries[id]??=[];entry.push(type);returnentries;},{});

ESLint Config

module.exports={parser:"@typescript-eslint/parser",rules:{"@typescript-eslint/no-unneccessary-condition":"error"},};

tsconfig

{"compilerOptions": {"strictNullChecks":true,"noUncheckedIndexedAccess":true  }}

Expected Result

Since entries has a type ofRecord<string, string[]> item fetched via index will give either an item or undefined.
TypeScript seems to recognize this

Actual Result

@typescript-eslint is under the impression that it will always get a result from accessing the object via index and flags the use of??= as an unnecessary condition.

Additional Info

No response