Suppress warnings when cache path does not exist. (#608)

* Added an exception clause that catches `FileNotFoundError` and logs a debug message in `SpotifyOAuth.get_cached_token`, `SpotifyPKCE.get_cached_token` and `SpotifyImplicitGrant.get_cached_token`.

* Changed docs for `auth` parameter of `Spotify.init` to `access token` instead of `authorization token`. In issue #599, a user confused the access token with the authorization code.

* Updated CHANGELOG.md

* Removed `FileNotFoundError` because it does not exist in python 2.7 (*sigh*) and replaced it with a call to `os.path.exists`.

* Replaced ` os.path.exists` with `error.errno == errno.ENOENT` to supress errors when the cache file does not exist.

spotipy/client.py

@@ -114,7 +114,7 @@ class Spotify(object):
         """
         Creates a Spotify API client.
 
-        :param auth: An authorization token (optional)
+        :param auth: An access token (optional)
         :param requests_session:
             A Requests session object or a truthy value to create one.
             A falsy value disables sessions.

spotipy/oauth2.py

@@ -11,6 +11,7 @@ __all__ = [
 ]
 
 import base64
+import errno
 import json
 import logging
 import os
@@ -305,9 +306,11 @@ class SpotifyOAuth(SpotifyAuthBase):
                 token_info = self.refresh_access_token(
                     token_info["refresh_token"]
                 )
-
-        except IOError:
-            logger.warning("Couldn't read cache at: %s", self.cache_path)
+        except IOError as error:
+            if error.errno == errno.ENOENT:
+                logger.debug("cache does not exist at: %s", self.cache_path)
+            else:
+                logger.warning("Couldn't read cache at: %s", self.cache_path)
 
         return token_info
 
@@ -784,9 +787,11 @@ class SpotifyPKCE(SpotifyAuthBase):
                 token_info = self.refresh_access_token(
                     token_info["refresh_token"]
                 )
-
-        except IOError:
-            logger.warning("Couldn't read cache at: %s", self.cache_path)
+        except IOError as error:
+            if error.errno == errno.ENOENT:
+                logger.debug("cache does not exist at: %s", self.cache_path)
+            else:
+                logger.warning("Couldn't read cache at: %s", self.cache_path)
 
         return token_info
 
@@ -1029,9 +1034,11 @@ class SpotifyImplicitGrant(SpotifyAuthBase):
 
             if self.is_token_expired(token_info):
                 return None
-
-        except IOError:
-            logger.warning("Couldn't read cache at: %s", self.cache_path)
+        except IOError as error:
+            if error.errno == errno.ENOENT:
+                logger.debug("cache does not exist at: %s", self.cache_path)
+            else:
+                logger.warning("Couldn't read cache at: %s", self.cache_path)
 
         return token_info