Yes, your are right; my concern was different.

The value you see is the EMPTY value, i.e. that there is no value assigned for the indicator at the bar. From looking at the code, apparently the indicator only assigns value at the bars where the arrows appear, and leav the value as EMPTY otherwise.

It could make sense to add "SetIndexEmptyValue(0,0);" and "SetIndexEmptyValue(1,0);" in the init() function, and thereby define the unassigned value to read as 0.