Only negative radius allowed for //butcher is -1.

worldedit-core/src/main/java/com/sk89q/worldedit/command/UtilityCommands.java

@@ -395,6 +395,10 @@ public class UtilityCommands {
         // there might be a better way to do this but my brain is fried right now
         if (args.argsLength() > 0) { // user inputted radius, override the default
             radius = args.getInteger(0);
+            if (radius < -1) {
+                actor.printError("Use -1 to remove all mobs in loaded chunks");
+                return;
+            }
             if (config.butcherMaxRadius != -1) { // clamp if there is a max
                 if (radius == -1) {
                     radius = config.butcherMaxRadius;