Find a cell that has a null value, and replace with an empty string.

I have a file that is 3 columns, and traverse the 3rd column, find a keyword, and then calculate the median of the values in column 2 between that keyword and the next keyword.

Here is the code that gives me the output I need:

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My problem comes when

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references the empty section of column 2 in the file.
The output for these values is "#NUM!". Is there an easy way to delete that so it's more appealing to the eye?

Thanks in advance for any advice!