In my experience, dynamic typing has not caused unforseen bugs at run time.
What it does do, is it causes large codebases to become extremely difficult to reason about, as you could get very little information about what types are needed or received where, and program flow, from the code.
Where I work, the managers decided that everything shall be python or ruby. So we have some 10,000+ line codebases, which are very hard to reason about. Including industrial control programs. "garbage collection pauses? What are those?"
This just happens in every programming language. I can tell you because the large Haskell systems I worked on were also incredibly hard to reason about. The analog of garbage collector pauses was accidental misuse of eager evaluation, but buried in misdirection through a sequence of specialized implementations that get called due to type class.
Big codebases becoming ugly messes is sociological and pressured by bureaucracy. It is not something that stricter language designs can seriously mitigate, even a little. Meanwhile, very disciplined and experienced teams can avoid it in virtually any programming language.
Some of the cleanest and safest huge software systems I’ve ever worked with were written in C, C++ or Python. Also some of the worst huge systems I’ve seen were written in C, C++ or Python.
I find getting as much tooling as possible that will tell you about types is pretty important with a large code base. For example in the Python code getting type annotations along with mypy up and running tends to be a big win.
In my experience, dynamic typing has not caused unforseen bugs at run time.
What it does do, is it causes large codebases to become extremely difficult to reason about, as you could get very little information about what types are needed or received where, and program flow, from the code.
Where I work, the managers decided that everything shall be python or ruby. So we have some 10,000+ line codebases, which are very hard to reason about. Including industrial control programs. "garbage collection pauses? What are those?"