The behavior for handling missing values. The supported values are:
- "gap" - the plot stops before the missing point and continues after it.
- "interpolate" - the value is interpolated from neighboring points.
- "zero" - the value is assumed to be zero.
The default value is "interpolate", except for "area" and stacked series which default to "zero".
missingValuesoption is supported when series.type is set to "area" and "line".