Handle more errors

Internal Server Error: /ipv6/work/signup/
Traceback (most recent call last):
  File "/home/app/pyvenv/lib/python3.5/site-packages/django/core/handlers/exception.py", line 34, in inner
    response = get_response(request)
  File "/home/app/pyvenv/lib/python3.5/site-packages/django/core/handlers/base.py", line 126, in _get_response
    response = self.process_exception_by_middleware(e, request)
  File "/home/app/pyvenv/lib/python3.5/site-packages/django/core/handlers/base.py", line 124, in _get_response
    response = wrapped_callback(request, *callback_args, **callback_kwargs)
  File "./users/views.py", line 19, in signup
    create_user(username, raw_password, first_name, last_name, email)
  File "./users/ldap_funcs.py", line 18, in create_user
    uidNumber = get_max_uid() + 1
  File "./users/ldap_funcs.py", line 79, in get_max_uid
    return int(handler.read())
ValueError: invalid literal for int() with base 10: ''

users/ldap_funcs.py

@@ -76,9 +76,21 @@ def get_max_uid():
     """
     try:
         with open(settings.LDAP_MAX_UID_PATH, 'r+') as handler:
-            return int(handler.read())
+            try:
+                return_value = int(handler.read())
+            except ValueError as ve:
+                logger.error(
+                    "Error reading int value from {}. {}"
+                    "Returning default value {} instead".format(
+                        settings.LDAP_MAX_UID_PATH,
+                        str(ve),
+                        settings.LDAP_DEFAULT_START_UID
+                    )
+                )
+                return_value = settings.LDAP_DEFAULT_START_UID
+            return return_value
     except FileNotFoundError as fnfe:
         logger.error("File not found : " + str(fnfe))
-        ret = settings.LDAP_DEFAULT_START_UID
-        logger.error("So, returing UID={}".format(ret))
-        return ret
+        retrun_value = settings.LDAP_DEFAULT_START_UID
+        logger.error("So, returning UID={}".format(retrun_value))
+        return retrun_value