fix: add-schedule on non existing host

This was failing with a non descriptive exception as we were trying
to access the host.broken parameter on a None type object when the
host is not found on DB.
Resolved to display a proper validation error.

Change-Id: I5f820180e6795fd5b16a3c3d765d2ca1c53471cf

quads/api_v2.py

@@ -379,10 +379,12 @@ def POST(self, **data):
 
         _host = data["host"]
         _host_obj = Host.objects(name=_host).first()
+        if not _host_obj:
+            result.append(f"Host {_host} is not defined")
 
         broken_hosts = Host.objects(broken=True)
         if _host_obj in broken_hosts:
-            result.append(f"Host {_host_obj.name} is in broken state")
+            result.append(f"Host {_host_obj.name} does not exist")
 
         # Check if there were data validation errors
         if result:

quads/model.py

@@ -283,6 +283,8 @@ def insert_schedule(self, cloud, host, start, end):
     @queryset_manager
     def is_host_available(self, queryset, host, start, end, exclude=None):
         _host = Host.objects(name=host).first()
+        if not _host:
+            return False
         if _host.broken or _host.retired:
             return False
         _query = Q(host=_host)