Using sensivity_ews it can happen that the fourth plot can not be created since only one P-value exists (third plot). In this case no output matrix for the sensivity is given and an error message is displayed Error in image.default(ix, iy, iz, xaxt = "n", yaxt = "n", xlab = "", : increasing 'x' and 'y' values expected
This problem can be "solved" by using the source code and commenting out the plotting part to get the output matrix.