[b84330808]

pad with an empty padding string never returns:

let x = "hello";
x.pad(10, "");   // never returns

pad_with_string appends padding until the character count reaches len, but an empty padding adds nothing, so the while loop never ends. The loop runs inside the native function, so max_operations and on_progress can't interrupt it: with set_max_operations(1_000), set_max_string_size(100) and an on_progress callback that terminates after 20 operations, the script above still hangs. For an engine that runs untrusted scripts, that's an easy way to lock up the host thread.

The fix returns early when padding is empty and leaves the string unchanged, the same as when len isn't larger than the string. The doc comment now says so.

Added test_string_pad to tests/string.rs. Without the fix it never finishes; with it, it passes. cargo test --tests passes, and the string tests also pass with no_object, no_index, unchecked, sync and internals,grain.

Found by calling every standard-library function with edge-case arguments; this was the only hang or panic it turned up.

I didn't add a CHANGELOG entry because 1.27.0 is already released and there's no section for the next version yet. Happy to add one wherever you prefer.

I used Claude Code to write this change.