Promise object results in different type with await/then

This code compiles

import yargs from "yargs";

const parser = yargs(process.argv.slice(2)).
    usage("$0 [filename]").
    demandCommand(1);

async function main() {
    const argv = await parser.argv;
}

while this does not

import yargs from "yargs";

const parser = yargs(process.argv.slice(2)).
    usage("$0 [filename]").
    demandCommand(1);

parser.argv.then(argv => {});

with compile errors

src/index.ts:13:1 - error TS18046: 'parser.argv.then' is of type 'unknown'.

13 parser.argv.then(argv => {});
   ~~~~~~~~~~~~~~~~

src/index.ts:13:18 - error TS7006: Parameter 'argv' implicitly has an 'any' type.

13 parser.argv.then(argv => {});
                    ~~~~

My language server reports that type of parser.argv is

(property) yargs.Argv<{}>.argv: {
    [x: string]: unknown;
    _: (string | number)[];
    $0: string;
} | Promise<{
    [x: string]: unknown;
    _: (string | number)[];
    $0: string;
}>

I thought awaiting on promise object and .thening on promise object would result in same type but it did not. Does await/then behave in different ways in Typescript?

Seems that parser.argv is not a promise at runtime.

While you can await any value, you can only call .then() on a promise (or then-able, aka an object with a then method).

If you want to ensure a promise value, you can wrap it with Promise.resolve()

Promise.resolve(parser.argv).then((argv) => {
  // ...
});