Fix case of hook being not registerd

python/dune/perftool/generation/hooks.py

@@ -12,5 +12,5 @@ def register_hook(hookname, func):
 
 
 def run_hook(hookname, *args, **kwargs):
-    for hook in _hooks[hookname]:
+    for hook in _hooks.get(hookname, ()):
         hook(*args, **kwargs)