Fix the examples to unwrap the error.

examples/src/3d/main.rs

@@ -194,7 +194,7 @@ fn game_tick(
             },
 
         },
-    );
+    ).unwrap();
 
     // update blackboard
     let db = bt.get_blackboard();

examples/src/async_drone/main.rs

@@ -180,7 +180,7 @@ async fn drone_tick(
                 }
             },
         }
-    );
+    ).unwrap();
 }
 
 #[tokio::main]

examples/src/boids/boid.rs

@@ -172,5 +172,5 @@ pub fn game_tick(dt: f32, cursor: mint::Point2<f32>, boid: &mut Boid, other_boid
             },
         }
 
-    });
+    }).unwrap();
 }

examples/src/simple_npc_ai/main.rs

@@ -58,7 +58,7 @@ fn game_tick(bt: &mut BT<EnemyNPC, BlackBoardData>, state: &mut EnemyNPCState) -
                 (Success, 0.0)
             }
         }
-    });
+    }).unwrap();
 
     // return status:
     status.0