Make sure offspring organisms are deleted if DoBirth fails.

source/Evolve/World.h

@@ -18,6 +18,7 @@
  *        facilitate demes, pools, islands, etc.
  *  @todo We should be able to have any number of systematics managers, based on various type_trait
  *        information a that we want to track.
+ *  @todo Add a signal for DoBirth() for when a birth fails.
  */
 
 #ifndef EMP_EVO_WORLD_H
@@ -1024,7 +1025,13 @@ namespace emp {
     Ptr<ORG> new_org = NewPtr<ORG>(mem);
     offspring_ready_sig.Trigger(*new_org);
     const OrgPosition pos = fun_add_birth(new_org, parent_pos);
-    if (pos.IsActive()) org_placement_sig.Trigger(pos.GetIndex());
+    if (pos.IsActive()) {
+      // If organism was placed right into the active population, trigger placement signal.
+      org_placement_sig.Trigger(pos.GetIndex());
+    } else if (!pos.IsValid()) {
+      // Organism failed to be placed in the population.  Delete it.
+      new_org.Delete();
+    }
     // SetupOrg(*new_org, &callbacks, pos);
     return pos;
   }