fix: Do not mutate tokens when creating details

[kamilogorek]

Input:

import { assertEquals } from "https://deno.land/std@0.166.0/testing/asserts.ts";

assertEquals(`foo bar`, `fooo baz`);

Before:

-   foo bar
+   fooobaz

After:

-   foo bar
+   fooo baz

---

Input:

import { assertEquals } from "https://deno.land/std@0.166.0/testing/asserts.ts";

assertEquals(`foo bar`, `foo baz`);

Before/after:

-   foo bar
+   foo baz

[CLAassistant]

All committers have signed the CLA.

[kamilogorek]

Oh, thanks @kt3k

[kt3k]

LGTM. Thanks!