Very badly formed SPDX generates exceptions other than SPDXParsingError

[king-doug-conti]

The README says that when using parse_file() from parse_anything.py "Unsuccessful parsing will raise SPDXParsingError with a list of all encountered problems." However, other Exceptions can be raised for very badly formed files.

As an example, if the SPDX file is a valid JSON format, and there is a string where an array or object should be, it issues:

AttributeError: 'str' object has no attribute 'get'

In my test case, I took a valid spdx.json file, and replaced a package with a string value:

    # self.json_data is valid spdx in json format
    bad_spdx = json.loads(self.json_data)
    bad_spdx['packages'][0] = 'bad value'
    bad_spdx_json = json.dumps(bad_spdx) 

    with open("spdx.json", 'w') as f:
        f.write(bad_spdx_json)

    parse_file("spdx.json")

I would expect such a case to raise an SPDXParsingError with an indication like "packages[0] was expected to be an array, but was not"