hmp: Ignore Error objects where the return value suffices

qdev_print_props() receives and throws away Error objects just to
check for object_property_get_str() and object_property_print()
failure.  Unnecessary, both return suitable values, so use those
instead.

Signed-off-by: Markus Armbruster <[email protected]>
Reviewed-by: Eric Blake <[email protected]>
Message-Id: <[email protected]>

Author: Markus Armbruster

qdev-monitor.c

@@ -697,22 +697,22 @@ static void qdev_print_props(Monitor *mon, DeviceState *dev, Property *props,
     if (!props)
         return;
     for (; props->name; props++) {
-        Error *err = NULL;
         char *value;
         char *legacy_name = g_strdup_printf("legacy-%s", props->name);
+
         if (object_property_get_type(OBJECT(dev), legacy_name, NULL)) {
-            value = object_property_get_str(OBJECT(dev), legacy_name, &err);
+            value = object_property_get_str(OBJECT(dev), legacy_name, NULL);
         } else {
-            value = object_property_print(OBJECT(dev), props->name, true, &err);
+            value = object_property_print(OBJECT(dev), props->name, true,
+                                          NULL);
         }
         g_free(legacy_name);
 
-        if (err) {
-            error_free(err);
+        if (!value) {
             continue;
         }
         qdev_printf("%s = %s\n", props->name,
-                    value && *value ? value : "<null>");
+                    *value ? value : "<null>");
         g_free(value);
     }
 }