Resolve "Loss function API"

Closes #9 (closed)

include/IMU/factor/factor_IMU.h

@@ -19,8 +19,8 @@ class FactorIMU : public FactorAutodiff<FactorIMU, 15, 3, 4, 3, 6, 3, 4, 3, 6>
     public:
         FactorIMU(const FeatureIMUPtr& _ftr_ptr,
                       const CaptureIMUPtr& _capture_origin_ptr,
-                      const ProcessorBasePtr& _processor_ptr = nullptr,
-                      bool _apply_loss_function = false,
+                      const ProcessorBasePtr& _processor_ptr,
+                      bool _apply_loss_function,
                       FactorStatus _status = FAC_ACTIVE);
 
         virtual ~FactorIMU() = default;