Update pretty.py

river/utils/pretty.py

@@ -34,7 +34,7 @@ def print_table(
         raise ValueError("all the columns must be of the same length")
 
     # Determine the width of each column based on the maximum length of it's elements
-    col_widths = [max(*map(len, col), len(header)) for header, col in zip(headers, columns)]
+    col_widths = [max(len(col) if col else 0, len(header)) for header, col in zip(headers, columns)]
 
     # Make a template to print out rows one by one
     row_format = " ".join(["{:" + str(width + 2) + "s}" for width in col_widths])