Currently the return value of write is broken, it never returns the

previous frame even when present.

This happens because a slice of length 64 is always passed to Frame::new
from within the `abort_pending_mailbox` function, causing `Frame::new`
to return None.

The fix is to take a subslice of length `data_length`.

.gitignore

@@ -5,3 +5,4 @@ Cargo.lock
 third_party
 /Cargo.toml
 out/
+.zed

embassy-stm32/src/can/fd/peripheral.rs

@@ -200,7 +200,7 @@ impl Registers {
             if header_reg.rtr().bit() {
                 F::new_remote(id, len as usize)
             } else {
-                F::new(id, &data)
+                F::new(id, &data[0..(len as usize)])
             }
         } else {
             // Abort request failed because the frame was already sent (or being sent) on