Raise type error instead of silencing it

Instead of skipping the type error when invalid
configuration values are provided instead we should
just let the user know about these errors and let
said user handle them appropriatly (by not passing
in invalid configuration).

Change-Id: Id17258e5e06b47bcabd2bfd9d02b9d21181244be

taskflow/persistence/backends/impl_sqlalchemy.py

@@ -210,11 +210,9 @@ class SQLAlchemyBackend(base.Backend):
             'convert_unicode': misc.as_bool(conf.pop('convert_unicode', True)),
             'pool_recycle': 3600,
         }
-        try:
-            idle_timeout = misc.as_int(conf.pop('idle_timeout', None))
+        if 'idle_timeout' in conf:
+            idle_timeout = misc.as_int(conf.pop('idle_timeout'))
             engine_args['pool_recycle'] = idle_timeout
-        except TypeError:
-            pass
         sql_connection = conf.pop('connection')
         e_url = sa.engine.url.make_url(sql_connection)
         if 'sqlite' in e_url.drivername:
@@ -228,10 +226,8 @@ class SQLAlchemyBackend(base.Backend):
             for (k, lookup_key) in [('pool_size', 'max_pool_size'),
                                     ('max_overflow', 'max_overflow'),
                                     ('pool_timeout', 'pool_timeout')]:
-                try:
-                    engine_args[k] = misc.as_int(conf.pop(lookup_key, None))
-                except TypeError:
-                    pass
+                if lookup_key in conf:
+                    engine_args[k] = misc.as_int(conf.pop(lookup_key))
         # If the configuration dict specifies any additional engine args
         # or engine arg overrides make sure we merge them in.
         engine_args.update(conf.pop('engine_args', {}))