Use generic db exceptions rather than sqlite3 specific ones

synapse/storage/directory.py

@@ -21,8 +21,6 @@ from twisted.internet import defer
 
 from collections import namedtuple
 
-import sqlite3
-
 
 RoomAliasMapping = namedtuple(
     "RoomAliasMapping",
@@ -91,7 +89,7 @@ class DirectoryStore(SQLBaseStore):
                 },
                 desc="create_room_alias_association",
             )
-        except sqlite3.IntegrityError:
+        except self.database_engine.module.IntegrityError:
             raise SynapseError(
                 409, "Room alias %s already exists" % room_alias.to_string()
             )

synapse/storage/registration.py

@@ -15,8 +15,6 @@
 
 from twisted.internet import defer
 
-from sqlite3 import IntegrityError
-
 from synapse.api.errors import StoreError, Codes
 
 from ._base import SQLBaseStore, cached
@@ -76,7 +74,7 @@ class RegistrationStore(SQLBaseStore):
             txn.execute("INSERT INTO users(name, password_hash, creation_ts) "
                         "VALUES (?,?,?)",
                         [user_id, password_hash, now])
-        except IntegrityError:
+        except self.database_engine.module.IntegrityError:
             raise StoreError(
                 400, "User ID already taken.", errcode=Codes.USER_IN_USE
             )