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• 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.
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Link to the rule's documentation

https://typescript-eslint.io/rules/no-floating-promises/

Description

Fastify.reply object has then method, but reply is not a Promise and its methods are not asynchronous

typescript-eslint marks each method of the reply object as asynchronous and requires it to be preceded by an await call

Fail

import { FastifyReply, FastifyRequest } from 'fastify';

function setNotFound(req: FastifyRequest, res: FastifyReply, done: HookHandlerDoneFunction): void {
    res.status(404);
    res.send('Not found');

    done();
}

Pass

import { FastifyReply, FastifyRequest } from 'fastify';

function setNotFound(req: FastifyRequest, res: FastifyReply, done: HookHandlerDoneFunction): void {
    void res.status(404);
    void res.send('Not found');

    done();
}

Additional Info

The plugin should look at what the object's method returns, and not just whether the object has a then method.

Or it is necessary to configure the rule to be able to exclude this object/methods from consideration by this rule