I am trying to create a custom shader for my object which has bones for skin animation. Below is my vertex shader.

attribute vec4 a_position;
attribute vec4 a_blendWeight;
attribute vec4 a_blendIndex;

const int SKINNING_JOINT_COUNT = 60;

uniform vec4 u_color;
uniform vec4 u_matrixPalette[SKINNING_JOINT_COUNT * 3];

#ifdef GL_ES
varying lowp vec4 v_fragmentColor;
#else
varying vec4 v_fragmentColor;
#endif


vec4 getPosition()
{
    float blendWeight = a_blendWeight[0];

    int matrixIndex = int (a_blendIndex[0]) * 3;
    vec4 matrixPalette1 = u_matrixPalette[matrixIndex] * blendWeight;
    vec4 matrixPalette2 = u_matrixPalette[matrixIndex + 1] * blendWeight;
    vec4 matrixPalette3 = u_matrixPalette[matrixIndex + 2] * blendWeight;
    
    
    blendWeight = a_blendWeight[1];
    if (blendWeight > 0.0)
    {
        matrixIndex = int(a_blendIndex[1]) * 3;
        matrixPalette1 += u_matrixPalette[matrixIndex] * blendWeight;
        matrixPalette2 += u_matrixPalette[matrixIndex + 1] * blendWeight;
        matrixPalette3 += u_matrixPalette[matrixIndex + 2] * blendWeight;
        
        blendWeight = a_blendWeight[2];
        if (blendWeight > 0.0)
        {
            matrixIndex = int(a_blendIndex[2]) * 3;
            matrixPalette1 += u_matrixPalette[matrixIndex] * blendWeight;
            matrixPalette2 += u_matrixPalette[matrixIndex + 1] * blendWeight;
            matrixPalette3 += u_matrixPalette[matrixIndex + 2] * blendWeight;
            
            blendWeight = a_blendWeight[3];
            if (blendWeight > 0.0)
            {
                matrixIndex = int(a_blendIndex[3]) * 3;
                matrixPalette1 += u_matrixPalette[matrixIndex] * blendWeight;
                matrixPalette2 += u_matrixPalette[matrixIndex + 1] * blendWeight;
                matrixPalette3 += u_matrixPalette[matrixIndex + 2] * blendWeight;
            }
        }
    }

    vec4 _skinnedPosition;
    vec4 position = vec4(a_position, 1.0);
    _skinnedPosition.x = dot(position, matrixPalette1);
    _skinnedPosition.y = dot(position, matrixPalette2);
    _skinnedPosition.z = dot(position, matrixPalette3);
    _skinnedPosition.w = position.w;
    
    return _skinnedPosition;
}

void main()
{
    vec4 position = getPosition();
    gl_Position = CC_MVPMatrix * position;
    v_fragmentColor = u_color;
}

However when I try to run it on Android, I get this glCompileShader error: S0008: Argument unused in the constructor. What can I do in this situation? After the shader is being compiled, cocos has automatically added some uniform values above such as CC_MVMatrix, CC_Time. Can it be the reason that cause this error above?