1305: Fix type error in row number assignment to handle NaN values

[alexfurmenkov]

No description provided.

[RamilCDISC]

Could you please add a description. I looked at connected issue and the title of the PR. I see you found a problem and did a fix. If you could add a small description of observed problem and what fix you applied for it, that would make understanding the PR easier for review.

[alexfurmenkov]

Hi @RamilCDISC,
The file that Hajime shared in the task did not reproduce the issue. I started trying to reproduce the problem myself, and I was able to do so - if I set data_contents_long_df['variable_name'] = '' in the debugger, the issue described by Hajime is reproduced.

[RamilCDISC]

The PR adds a null check for robustness. The connected ticket issue was not reproduced. The PR enhances a check by adding a null check on top.