Add IOError custom message when rsa key file is missing.

oidc_provider/lib/utils/common.py

@@ -22,7 +22,10 @@ def get_rsa_key():
     Load the rsa key previously created with `creatersakey` command.
     """
     file_path = settings.get('OIDC_RSA_KEY_FOLDER') + '/OIDC_RSA_KEY.pem'
-    with open(file_path, 'r') as f:
-        key = f.read()
+    try:
+        with open(file_path, 'r') as f:
+            key = f.read()
+    except IOError:
+        raise IOError('We could not find your key file on: ' + file_path)
 
     return key