message: calib3d: Fix calibrateCamera() misleading error
  objectPoints and imagePoints are not checked whether they're empty and
  cause checkVector() to fail, thus result in a wrong error message.
  Fixes:
diff: @@ -3141,10 +3141,17 @@ static void collectCalibrationData( InputArrayOfArrays objectPoints,
  for( i = 0; i < nimages; i++ )
  {
  - ni = objectPoints.getMat(i).checkVector(3, CV_32F);
  + Mat objectPoint = objectPoints.getMat(i);
  + if (objectPoint.empty())
  + CV_Error(CV_StsBadSize, "objectPoints should not contain empty vector of vectors of points");
  + ni = objectPoint.checkVector(3, CV_32F);
  if( ni <= 0 )
  CV_Error(CV_StsUnsupportedFormat, "objectPoints should contain vector of vectors of points of type Point3f");
  - int ni1 = imagePoints1.getMat(i).checkVector(2, CV_32F);
  +
  + Mat imagePoint1 = imagePoints1.getMat(i);
  + if (imagePoint1.empty())
  + CV_Error(CV_StsBadSize, "imagePoints1 should not contain empty vector of vectors of points");
  + int ni1 = imagePoint1.checkVector(2, CV_32F);
  if( ni1 <= 0 )
  CV_Error(CV_StsUnsupportedFormat, "imagePoints1 should contain vector of vectors of points of type Point2f");
  CV_Assert( ni == ni1 );
  