Show a nice error if the role name is missing.

lib/ansible/cli/galaxy.py

@@ -167,8 +167,8 @@ class GalaxyCLI(CLI):
         force      = self.get_opt('force', False)
         offline    = self.get_opt('offline', False)
 
-        role_name = self.args.pop(0).strip()
-        if role_name == "":
+        role_name = self.args.pop(0).strip() if self.args else None
+        if not role_name:
             raise AnsibleOptionsError("- no role name specified for init")
         role_path = os.path.join(init_path, role_name)
         if os.path.exists(role_path):