This code works on one machine and fails on another. How to debug?

Question

I have a function that looks like this:

def search_street_addresses(query, limit: 100)
  if query.is_a? String
    query = @address_parser.parse(query)

    fail ArgumentError, "Invalid address string" if query.nil?
  end

  # ...

And it's called like this:

begin
  results = @ndi.search_street_addresses(query)
rescue ArgumentError
  raise CommandError, "Failed to parse address"
end

It works perfectly on my machine. I have stepped through the code with a debugger, and everything works as expected. The problem is that on the machine of a co-worker (with the exact same code as I and the exact same Ruby version) a seemingly impossible thing happens. Between the call @ndi.search_street_addresses(query) and the first line of the function, an ArgumentError is raised. I have inserted a breakpoint like this:

begin
  require "byebug"; byebug
  results = @ndi.search_street_addresses(query)
# ...

And attempted to step into the function, but the ArgumentError is raised after the first step I take, without me ever entering the function. I have also set a breakpoint in the function:

def search_street_addresses(query, limit: 100)
  require "byebug"; byebug
  if query.is_a? String
    # ...

But the ArgumentError is raised without the breakpoint triggering. This only happens on his machine, everything works perfectly on mine. I don't have the slightest clue how to debug this since the ArgumentError is seemingly raised somewhere in the Ruby ether outside the reach of Byebug.

So; how do I debug this?

Answer 1

Anticlimactic answer; my co-worker reinstalled Ruby and now everything works. I'm not sure whether to delete this question or leave this answer to perhaps save a couple of hours of pointless debugging for somebody else.