runtime issues when adding shapefile

[matthewellis02]

Exception in Tkinter callback
Traceback (most recent call last):
  File "/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/lib-tk/Tkinter.py", line 1547, in __call__
    return self.func(*args)
  File "main_menu.py", line 68, in __openShpfile
    dbfFile = dbf.DbfLoader(directory[:-3] + "dbf")
  File "/Users/matthewellis/Downloads/Python-Tool-Sample-py3-main/dbfload.py", line 65, in __init__
    if (dbfFileName): self.loadDbfFileName(dbfFileName)
  File "/Users/matthewellis/Downloads/Python-Tool-Sample-py3-main/dbfload.py", line 71, in loadDbfFileName
    self.loadDbfFile(dbfs)
  File "/Users/matthewellis/Downloads/Python-Tool-Sample-py3-main/dbfload.py", line 80, in loadDbfFile
    self.readHeaderData(dbfFile)
  File "/Users/matthewellis/Downloads/Python-Tool-Sample-py3-main/dbfload.py", line 96, in readHeaderData
    fieldCount = (self.headerLength - 33) / 32
TypeError: unsupported operand type(s) for -: 'str' and 'int'