Rust text or trace and format! throws RuntimeError: unreachable executed

[FreeMasen]

When attempting to draw dynamic text to the screen in rust, the runtime aborts entirely.

// lib.rs
mod wasm4;
use wasm4::*;

#[no_mangle]
fn update() {
    unsafe {
        *DRAW_COLORS = 2;
    }
    text(format!("{:02x}", unsafe {CT}).as_str(), 10, 10);
    unsafe { CT += CT.wrapping_add(1) }
}

Error in the console:

Uncaught (in promise) RuntimeError: unreachable executed
    update http://localhost:4444/wasm4.js:1
    t http://localhost:4444/wasm4.js:1
    <anonymous> http://localhost:4444/wasm4.js:1
    async* http://localhost:4444/wasm4.js:1
    <anonymous> http://localhost:4444/wasm4.js:1
wasm4.js line 1 > WebAssembly.instantiate:15530:1
    <anonymous> http://localhost:4444/wasm4.js:1
    AsyncFunctionNext self-hosted:692
    (Async: async)
    <anonymous> http://localhost:4444/wasm4.js:1
    <anonymous> http://localhost:4444/wasm4.js:1

[aduros]

Hmm, it looks like any heap allocation in Rust isn't working. Looking at the call stack, it seems to be hitting a function called $rust_oom, which suggests "out of memory".

I wonder if Rust's allocator is trying to prereserve a block of memory larger than available in this constrained environment.