@std/toml: Inline array stringification mishandles edge cases

[Aplet123]

Inline array stringification has multiple bugs in the current implementation. Running:

import * as toml from "@std/toml";

// Primitive array bugs
console.log(toml.stringify({x: [Infinity, -Infinity, NaN]}));
console.log(toml.stringify({x: [new Date(0)]}));

// Object-only array bug
try {
    console.log(toml.stringify({x: [null]}));
} catch (e) {
    console.log("got error", e);
}

// Mixed-type array bugs
console.log(toml.stringify({x: [Infinity, -Infinity, NaN, {}]}));
console.log(toml.stringify({x: [new Date(0), {}]}));
try {
    console.log(toml.stringify({x: [1, null]}));
} catch (e) {
    console.log("got error", e);
}

Will log:

x = [null,null,null] // expected: x = [inf, -inf, nan]

x = ["1970-01-01T00:00:00.000Z"] // expected: x = [1970-01-01T00:00:00.000Z]

got error TypeError: Cannot convert undefined or null to object // expected: ???
    at Object.keys (<anonymous>)
    at Dumper.#printObject (https://jsr.io/@std/toml/1.0.11/stringify.ts:51:26)
    at Dumper.#printObject (https://jsr.io/@std/toml/1.0.11/stringify.ts:83:42)
    at Dumper.dump (https://jsr.io/@std/toml/1.0.11/stringify.ts:45:36)
    at Module.stringify (https://jsr.io/@std/toml/1.0.11/stringify.ts:294:26)

x = [Infinity,-Infinity,NaN,{}] // expected: x = [inf, -inf, nan, {}]

x = ["1970-01-01T00:00:00.000",{}] // expected: x = [1970-01-01T00:00:00.000Z, {}]

got error Error: Should never reach // expected: ???
    at Dumper.#printAsInlineValue (https://jsr.io/@std/toml/1.0.11/stringify.ts:151:15)
    at https://jsr.io/@std/toml/1.0.11/stringify.ts:87:64
    at Array.map (<anonymous>)
    at Dumper.#printObject (https://jsr.io/@std/toml/1.0.11/stringify.ts:87:29)
    at Dumper.dump (https://jsr.io/@std/toml/1.0.11/stringify.ts:45:36)
    at Module.stringify (https://jsr.io/@std/toml/1.0.11/stringify.ts:294:26)

Since TOML doesn't support null values, I'm not sure how the {x: [null]} and {x: [1, null]} cases should be handled, but I feel at the very least a better error message should be given. The quotation marks around the date is a somewhat minor bug as it causes the date to reparse as a string instead of a Date. The mishandling of Infinity/NaN is a more severe bug as both cases (stringifying to null and stringifying to Infinity/NaN) causes it to no longer parse.

I can attempt a PR to fix this, but I'm wondering if it's even necessary to stringify "primitive" arrays using JSON.stringify. This is causing the first 2 bugs here, and I'm not sure that it meaningfully improves runtime compared to just using the mixed-type array stringification.

Environment

• OS: Arch Linux
• deno version: 2.8.1
• std version: 1.0.11