Format displayed number

test/src/main.rs

@@ -9,7 +9,7 @@ use riscv_rt::entry;
 fn panic_handler(_info: &PanicInfo) -> ! {
     NumberDisplay::display_number(0xDEADC0DE);
     let mut text = TextDisplay{};
-    let _ = write!(text, "Panic: {} 1234", _info.message());
+    let _ = write!(text, "Panic: {} {}", _info.message(), 1234);
     loop {}
 }