In order to display the native opencv’s error code, please enclose the code in Utils.setDebugMode(true) and Utils.setDebugMode(false).

Example Code:

            //
            // CVException handling example
            //

            // 32F, channels=1, 3x3
            Mat m1 = new Mat (3, 3, CvType.CV_32FC1);
            m1.put (0, 0, 1.0f, 2.0f, 3.0f, 4.0f, 5.0f, 6.0f, 7.0f, 8.0f, 9.0f);

            // 8U, channels=1, 3x3
            Mat m2 = new Mat (3, 3, CvType.CV_8UC1);
            m2.put (0, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9);

            // dump
            Debug.Log (""m1="" + m1);
            Debug.Log (""m1.dump()="" + m1.dump ());
            Debug.Log (""m2="" + m2);
            Debug.Log (""m2.dump()="" + m2.dump ());

            #if UNITY_STANDALONE || UNITY_EDITOR
            // Publish CVException to Debug.LogError.
            Utils.setDebugMode (true, false);
            Mat m3 = m1 / m2;
            Utils.setDebugMode (false);

            // Throw CVException.
            Utils.setDebugMode (true, true);
            try
            {
                Mat m4 = m1 / m2;
            }
            catch (Exception e)
            {
                Debug.Log (""CVException: "" + e);
            }
            Utils.setDebugMode (false);
            #else
            Debug.Log (""The setDebugMode method is only supported on WIN, MAC and LINUX."");
            #endif

Execution Result:

m1=Mat [ 3*3*CV_32FC1, isCont=True, isSubmat=False, nativeObj=0x820637680, dataAddr=0x820295296 ]
m1.dump()=[1, 2, 3;
 4, 5, 6;
 7, 8, 9]
m2=Mat [ 3*3*CV_8UC1, isCont=True, isSubmat=False, nativeObj=0x820637792, dataAddr=0x820619712 ]
m2.dump()=[  1,   2,   3;
   4,   5,   6;
   7,   8,   9]
   
core::divide_12() : OpenCV(3.4.1-dev) C:\Users\xxxxx\Desktop\opencv\modules\core\src\arithm.cpp:683: error: (-5) When the input arrays in add/subtract/multiply/divide functions have different types, the output array type must be explicitly specified in function cv::arithm_op
m3=Mat [ 0*0*CV_8UC1, isCont=False, isSubmat=False, nativeObj=0x820637568, dataAddr=0x0 ]

CVException: OpenCVForUnity.CvException: core::divide_12() : OpenCV(3.4.1-dev) C:\Users\satoo\Desktop\opencv\modules\core\src\arithm.cpp:683: error: (-5) When the input arrays in add/subtract/multiply/divide functions have different types, the output array type must be explicitly specified in function cv::arithm_op