Fix: Tackerclient failed to handle yaml load error.

While onboarding a vnfd with infected vnfd file, yaml.load() raised exception.
Due to which instead of giving meaningful error message, tackerclient raised
traces with TypeError.
Fixing this issue with proper error handling.

Change-Id: I7a4150a898fcf99d8ffbc97e16da6a219cade93d
Closes-Bug: #1780214

tackerclient/osc/v1/vnfm/vnfd.py

@@ -77,7 +77,8 @@ class CreateVNFD(command.ShowOne):
             try:
                 vnfd = yaml.load(vnfd, Loader=yaml.SafeLoader)
             except yaml.YAMLError as e:
-                raise exceptions.InvalidInput(e)
+                msg = _("yaml failed to load vnfd file. %s") % e
+                raise exceptions.InvalidInput(msg)
             if not vnfd:
                 raise exceptions.InvalidInput("vnfd file is empty")
             body[_VNFD]['attributes'] = {'vnfd': vnfd}