Better Error Messages (easy version)

[habermanUIUC]

When a student submits code that breaks a test but it's not due to an assertion error, the feedback is either confusing or misleading.

For example, if a student has a simple KeyError mistake

def my_code(dataframe):
   return dataframe['SalesPerson']  # assume SalesPerson is not a valid key

The test will fail but with the message:

"Test Failed: 'SalesPerson'

That really offers no help

Describe the solution you'd like
An easy solution is to provide the class of the exception or error:

"Test Failed: <class 'KeyError'> 'SalesPerson'\n"

The fix is simply in json_test_runner.py (buildResult) line 77

if err:
    if err[0] is AssertionError:
        output += "Test Failed: {0}\n".format(err[1])
    else:
        output += "Test Failed: {0} {1}\n".format(err[0], err[1])
# note that isinstance will NOT work here

Describe alternatives you've considered
A similar pull request
#18

However with that solution you get the following:

"Test Failed: 'SalesPerson'\nhashtable_class_helper.pxi:pandas._libs.hashtable.PyObjectHashTable.get_item line 1627: \n"

In this context, the backtrace is not helpful to the student. Perhaps a config option?

Also, in that pull request it should not use isinstance() to test the error class.
(tested in python3.6).

Additional context