Dataset with null-gaps: Error, if a value is null in dataset

[chr-dev]

Hi,

if the dataset contains "null" values (that means gaps), there is an error: "dataset[i] is null" in line 135:
arr[i] = dataset[i][1];

The dataset looks like this:
[
[1324339200000,490],
null,
[1327795200000,870],
[1327881600000,870],
[1327968000000,871],
null
]

Flot recognizes these null values and interrupts automatically the chart line at these points, produces so called gaps.

How can I use the multiple threshold plugin anyway?
I already tried to set arr[i] to null @ line 135, but didn't work... any help??

Best regards and thanks in advance,
Chris