FIX: Ignore non-numeric values when migrating from old data format

This fixes 'invalid input syntax for integer' errors when the old data is invalid

db/migrate/20190724055909_move_to_managed_authenticator.rb

@@ -17,6 +17,7 @@ class MoveToManagedAuthenticator < ActiveRecord::Migration[5.2]
       CURRENT_TIMESTAMP
     FROM plugin_store_rows
     WHERE plugin_name = 'oauth2_basic'
+    AND value::json->>'user_id' ~ '^[0-9]+$'
     ON CONFLICT (provider_name, user_id)
     DO NOTHING
     SQL