When changes are made to your web applications, they should be developed in a development environment, tested properly and then deployed. The last 2 steps (and several steps in between depending on your needs) can all be handled automatically using a combination of local/cloud development environments, github repositories and automated deployment systems (i.e., Jenkins, Bamboo). The more people you have on your team, the more important this is. When set up properly, you can be assured that if there are any problems, they will be found before the changes go live.