LJMError should be moved into its own exception module

[jbiams77]

by defining the same LJMError class in the module where it is used, there exists a chicken/egg problem where the LJMError cannot be used to catch exception when importing LJM library.

For example:

try:
    from labjack import ljm
except labjack.ljm.ljm.LJMError as exception:
    raise LabjackLibraryNotInstalled from exception

cannot work because the LJMError is defined in the same module. A better practice is to seperate the exception class into it's own module that only depends on Python standard library, this ensures Labjack package exceptions can be used for module imports that wrap library code, just as labjack-ljm-python wraps the LJM library that is required to be installed.

Another issue is that the _loadLibrary() function catches the LJMError exception, prints the error, then returns None. Why? If the python package doesn't work without the LJM library, then it shouldn't handle the exception, it should just raise it and let the calling module handle the exception.

Please remove from _loadLibrary():

    except LJMError:
        ljme = sys.exc_info()[1]
        print(str(type(ljme)) + ": " + str(ljme))
        return None

[gavinmccabe]

I had this same issue. I attempted a quick solution in #19 to fix this but haven't gotten any responses. Either way, #19 has a hacky workaround for any others reading this...

[davelopez01]

Sorry for not replying earlier and thank you for bringing up this issue. We are currently working on T8 release tasks. This is on our list of issues to look into soon.