Fix qemu_coverage v2 (#2882)

Author: rmalmain

fuzzers/binary_only/qemu_coverage/src/fuzzer.rs

@@ -180,7 +180,7 @@ pub fn fuzz() {
 
         let reset = |qemu: Qemu, buf: &[u8], len: GuestReg| -> Result<(), QemuRWError> {
             unsafe {
-                let _ = qemu.write_mem(input_addr, buf);
+                qemu.write_mem(input_addr, buf)?;
                 qemu.write_reg(Regs::Pc, test_one_input_ptr)?;
                 qemu.write_reg(Regs::Sp, stack_ptr)?;
                 qemu.write_return_address(ret_addr)?;
@@ -213,11 +213,6 @@ pub fn fuzz() {
                 let len = len as GuestReg;
                 reset(qemu, buf, len).unwrap();
 
-                unsafe {
-                    let ret = emulator.run(state, input);
-                    log::warn!("ret = {ret:?}");
-                }
-
                 ExitKind::Ok
             };