edit

demeter/model.py

@@ -172,6 +172,8 @@ class Model(object):
 			value = str(value)
 		if self.call:
 			value = self.call(key, value)
+		if value == None or not value:
+			value = ''
 		return value
 
 	def attr(self, method):

demeter/web.py

@@ -210,7 +210,8 @@ class Web(object):
 				result = method(self, *args, **kwargs)
 				return result
 			except Exception as e:
-				Demeter.echo(e)
+				import traceback
+				tracebak.print_exc()
 				try:
 					return self.view('404.html')
 				except Exception as e: