Anecdotes don't really count for much, of course, but the balance is against you, here. It is clearly and evidently true that when you refactor, static typing s

Anecdotes don't really count for much, of course, but the balance is against you, here. It is clearly and evidently true that when you refactor, static typing systems find a lot of errors that you would discover at runtime in dynamically-typed systems. It's true almost by definition. It can still be fine if you're being meticulous and know the codebase well enough, but otherwise, you'll miss corner cases in parts of the code with less test coverage or typical interaction. When you accidentally occasionally have a string in place of a number deep in some data structure, you might not notice for a long time.