fixes a reference to an outdated error type (#571)

* fixes a reference to an outdated error type

* reverts accidental trailing whitespace trimming

* reverts accidental trailing whitespace trimming

---------

Co-authored-by: Simon Stone <simon.stone@dartmouth.edu>

Author: Simon-Stone

episodes/04-data-types-and-format.md

@@ -283,8 +283,8 @@ Pandas cannot convert types from float to int if the column contains NaN values.
 
 ## Missing Data Values - NaN
 
-What happened in the last challenge activity? Notice that this throws a value error:
-`ValueError: Cannot convert NA to integer`. If we look at the `weight` column in the surveys
+What happened in the last challenge activity? Notice that this raises a casting error:
+`pandas.errors.IntCastingNaNError: Cannot convert non-finite values (NA or inf) to integer` (in older versions of pandas, this may be called a `ValueError` instead). If we look at the `weight` column in the surveys
 data we notice that there are NaN (**N**ot **a** **N**umber) values. **NaN** values are undefined
 values that cannot be represented mathematically. pandas, for example, will read
 an empty cell in a CSV or Excel sheet as `NaN`. NaNs have some desirable properties: if we