Got it... (had to turn off "panic_abort_immediate" to allow panics, and then comment out some code to let the application fit into flash...
```
ERROR panicked at ./firmware/cross-stm32wl-app/target/thumbv7em-none-eabi/debug/build/embassy-stm32-ea8b0cee25df8d1e/out/_generated.rs:609:48:called `Option::unwrap()` on a `None` value
```
which is in:
```rust
impl crate::rcc::SealedRccPeripheral for peripherals::I2C1 {
    fn frequency() -> crate::time::Hertz {
        unsafe { crate::rcc::get_freqs().pclk1.unwrap() }
    }
...
```
This code operates correctly in a release build, but panics in a debug build