While plotting charts, there is a default chart that is created automatically when we switch from table to chart view.
Then user selects first three yseries according to their requirement and plot a chart. Later, when the user removes the yseries1 and plot it. Then a default chart is created in which yseries2 and yseries3 are not present.
This can be improved by providing an error message that yseries1 can not be empty or by plotting a chart on basis of yseries2 and yseries3.
This is a default chart
a
Now we selected some yseries and clicked on plot and save
Now we removed yseries1 and click on plot and save. Chart is saved without any error.
Now, it is still showing chart as for the measure that is not even selected. And selected measures that are yseries2 and yseries3 are not there in the chart.