ERROR 'The truth value of a DataFrame is ambiguous'

[wook2014]

Description of the bug

An error occurred when running with spliz nextflow pipeline

ValueError: The truth value of a DataFrame is ambiguous. Use a.empty, a.bool(), a.item(), a.any() or a.all().

It seemed that the problem can be located in file calc_splizvd.py line 387

df["cov"] = df["gene"].map(grouped.apply(lambda x: x['z_Start'].cov(x['z_End'])))

And it should be like this

df["cov"] = df["gene"].map(grouped.apply(lambda x: x['z_Start'].cov(x['z_End'])).to_dict())

The very same problem also exists as mentioned in juliaolivieri/SpliZ_pipeline#10