AP_IOMCU: Ensure IOMCU does not log if there is no logger

libraries/AP_IOMCU/AP_IOMCU.cpp

@@ -328,14 +328,16 @@ void AP_IOMCU::read_status()
     uint32_t now = AP_HAL::millis();
     if (now - last_log_ms >= 1000U) {
         last_log_ms = now;
-        AP::logger().Write("IOMC", "TimeUS,Mem,TS,NPkt,Nerr,Nerr2,NDel", "QHIIIII",
-                           AP_HAL::micros64(),
-                           reg_status.freemem,
-                           reg_status.timestamp_ms,
-                           reg_status.total_pkts,
-                           total_errors,
-                           reg_status.num_errors,
-                           num_delayed);
+        if (AP_Logger::get_singleton()) {
+            AP::logger().Write("IOMC", "TimeUS,Mem,TS,NPkt,Nerr,Nerr2,NDel", "QHIIIII",
+                               AP_HAL::micros64(),
+                               reg_status.freemem,
+                               reg_status.timestamp_ms,
+                               reg_status.total_pkts,
+                               total_errors,
+                               reg_status.num_errors,
+                               num_delayed);
+        }
 #if IOMCU_DEBUG_ENABLE
         static uint32_t last_io_print;
         if (now - last_io_print >= 5000) {