Abstraction and composition are great to surface the main characteristics of your algorithm. A compiler then can take those characteristics and verify if they make sense. Different compilers can do that in different amounts, and the Javascript one does the absolute minimum possible. On this case, you get no safety, just more complex code.
Go ask a Haskell developer and the first reaction you will get is probably "wait, you were running getData inside the original function?!"
Haskell developer here, this was indeed my first reaction :P
I agree with the statement that composition won't make the code unreliable.
When I wrote mistake, the kind of mistake I was referring too was a mistake in abstraction boundaries, rather than execution. (for an extreme case consider a DSL: if you abstract a DSL from only one example, you'd likely get the core abstractions wrong)