Fix SimplePrintingMonitor (#1164)

libafl/src/monitors/mod.rs

@@ -319,12 +319,21 @@ impl Default for NopMonitor {
 
 #[cfg(feature = "std")]
 /// Tracking monitor during fuzzing that just prints to `stdout`.
-#[derive(Debug, Clone, Default)]
+#[derive(Debug, Clone)]
 pub struct SimplePrintingMonitor {
     start_time: Duration,
     client_stats: Vec<ClientStats>,
 }
 
+impl Default for SimplePrintingMonitor {
+    fn default() -> Self {
+        Self {
+            start_time: current_time(),
+            client_stats: Vec::new(),
+        }
+    }
+}
+
 #[cfg(feature = "std")]
 impl SimplePrintingMonitor {
     /// Create a new [`SimplePrintingMonitor`]