Stack Snippet console.warn can’t log Error objects (or other non-string, non-array objects passed as the first argument)

This Snippet should log two warnings:

(async () => {
  console.warn(new Error("blah"));
})();

console.warn(new Error("blah"));

but it actually logs one error:

Error: {
  "message": "Script error.",
  "filename": "https://stacksnippets.net/scripts/snippet-javascript-console.min.js?v=2",
  "lineno": 0,
  "colno": 0
}

In the native browser console, I see this, however:

Uncaught TypeError: e[0].indexOf is not a function
    warn https://stacksnippets.net/scripts/snippet-javascript-console.min.js?v=2:1
    <anonymous> https://stacksnippets.net/js:16
snippet-javascript-console.min.js:1:5319
    warn https://stacksnippets.net/scripts/snippet-javascript-console.min.js?v=2:1
    <anonymous> https://stacksnippets.net/js:16

Uncaught (in promise) TypeError: e[0].indexOf is not a function
    warn https://stacksnippets.net/scripts/snippet-javascript-console.min.js?v=2:1
    <anonymous> https://stacksnippets.net/js:13
    <anonymous> https://stacksnippets.net/js:14
snippet-javascript-console.min.js:1:5319

Browser: Firefox 128 ESR.

The culprit seems to be (from https://stacksnippets.net/scripts/snippet-javascript-console.js line 361 and following):

console.warn = function () {

    var args = arguments;

    // Since we are *intentionally* running this in-browser,
    // we can suppress this message as it's more annoying than helpful
    if (args[0].indexOf('You are using the in-browser Babel transformer') !== -1)
        return;

    /* […] */
};

This can be worked around by prepending a '%o' argument, but the workaround doesn’t work particularly well either, as it displays the error as “{}”:

console.warn('%o', new Error("blah"));