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=5.6.3&fileType=.tsx&code=CYUwxgNghgTiAEYD2A7AzgF3gMyhNIAngEICWA5gJIoYBc8ADCgNwBQp28AFLvkWVRoBKeAG9WAXyA&eslintrc=N4KABGBEBOCuA2BTAzpAXGUEKQAIBcBPABxQGNoBLY-AWhXkoDt8B6Jge1tiacTJTIAhtEK0yHJgBNK%2BSpPRQA7iKaRwYAL4hNQA&tsconfig=N4KABGBEDGD2C2AHAlgGwKYCcDyiAuysAdgM6QBcYoEEkJemy0eAcgK6qoDCAFutAGsylBm3TgwAXxCSgA&tokens=false

Repro Code

declareconstfalseyBigInt:0n;if(falseyBigInt){}

ESLint Config

module.exports={"rules":{"@typescript-eslint/no-unnecessary-condition":"warn"}}

tsconfig

{"compilerOptions": {"strictNullChecks":true  }}

Expected Result

Unnecessary conditional, value is always falsy.

Actual Result

Unnecessary conditional, value is always truthy.

Additional Info

This is a bug with this line.

The.value field returns aPseudoBigIntobject that looks like{ negative?: boolean, base10Value: string }, rather than abigint itself (for legacy TS support reasons). So checking for truthiness is incorrect; we need to convert to a real bigint.