Update error message in EnergySiteValidator

tkwantoperator/energy.pyx

@@ -50,7 +50,7 @@ class EnergySiteValidator:
     @cython.embedsignature
     def __init__(self, syst):      
         if not isinstance(syst, kwant.system.FiniteSystem):
-            raise ValueError("The argument given to 'syst' is not a kwant.system.FiniteSystem or a kwant.system.InfiniteSystem class instance.")
+            raise ValueError("The argument given to 'syst' is not a kwant.system.FiniteSystem class instance.")
         self.syst = syst
         
         self.interface_site_ids = {site_id for interface in syst.lead_interfaces for site_id in interface}