DebugPass.Mode enum is not used correctly in blit_debug.frag

[anne-gropler]

Definition of DebugPass.Mode:

export enum Mode {
        Depth = 0,
        DepthLinear = 1,
        DepthPacked = 2,
        DepthLinearPacked = 3,
    }

Usage in blit_debug.frag:

    if(u_mode == 1) {           /* Depth */
        source.rgb = vec3(source[0]);

    } else if (u_mode == 2) {   /* DepthLinear */
        float zLinear = linearizeDepth(source[0], u_linearize[0], u_linearize[1]);
        source.rgb = vec3(zLinear);

    } else if(u_mode == 3) {    /* DepthPacked */
        source.rgb = float24x1_to_uint8x3(source[0]);

    } else if (u_mode == 4) {   /* DepthLinearPacked */
        float zLinear = linearizeDepth(source[0], u_linearize[0], u_linearize[1]);
        source.rgb = float24x1_to_uint8x3(zLinear);
    }

Note that it is defined to start at 0, but in the shader it starts at 1.