How to understand an Index Error Message?

Question

I am attempting to use the pretty-print confusion-matrix library to create a confusion matrix.

When I run pp_matrix(df, cmap=cmap), I get the following error message:

Traceback (most recent call last):
  File "/Users/name/folder/subfolder/subsubfolder/prepositions.py", line 27, in <module>
    pp_matrix(df, cmap=cmap)
  File "/opt/anaconda3/lib/python3.8/site-packages/pretty_confusion_matrix/pretty_confusion_matrix.py", line 222, in pp_matrix
    txt_res = configcell_text_and_colors(
  File "/opt/anaconda3/lib/python3.8/site-packages/pretty_confusion_matrix/pretty_confusion_matrix.py", line 59, in configcell_text_and_colors
    tot_rig = array_df[col][col]
IndexError: index 37 is out of bounds for axis 0 with size 37

The first few lines of my DateFrame look like this:

               in   auf   mit   zu  ...  an-entlang  auf-entlang  ohne  außerhalb
into          318     8    10    9  ...           0            0     0          0
in           4325   727   681   62  ...           0            0     0          0
on            253  3197   215   46  ...           0            0     0          0
at            206   280    54    9  ...           0            0     0          0
with          384   397  2097   24  ...           0            0     0          0
by             31    12    23    0  ...           0            0     0          0
in-front-of    15    15    25    0  ...           0            0     0          0

The total size is 49 rows x 36 columns.

I think the issue has to do with zero-indexing in Python, but to be honest, I'm not even sure how to go about debugging this.

Any suggestions would be greatly appreciated. Thank you in advance.