You are missing the pair of parentheses after copy in line 25 – it should be copy(). (You can probably also simply omit the entire call to copy if you do not plan to modify either the input or the output table afterwards.)
The reported error is not directly triggered by your code but by the logic that transfers the node’s output data back to KNIME behind the scenes. One of the first things done there is to determine the size of output_table_1 in terms of its number of rows.