fix TypeError (hardbyte#1466)

Author: zariiii9003

can/interfaces/pcan/basic.py

@@ -658,7 +658,8 @@ def __init__(self):
         #
         if platform.system() == "Windows":
             # Loads the API on Windows
-            self.__m_dllBasic = windll.LoadLibrary(find_library("PCANBasic"))
+            _dll_path = find_library("PCANBasic")
+            self.__m_dllBasic = windll.LoadLibrary(_dll_path) if _dll_path else None
             aReg = winreg.ConnectRegistry(None, winreg.HKEY_LOCAL_MACHINE)
             try:
                 aKey = winreg.OpenKey(aReg, r"SOFTWARE\PEAK-System\PEAK-Drivers")