I got the impression that the bugs found were either not at all serious (e.g. throwing a typeerror on malformed input instead of some other nicer kind of error) or were in areas of the code not covered by tests.
Unfortunately the author does not rate them by severity.
My gut feeling is that dynamic typing + tests & static analysis is faster than very heavyweight languages (e.g. Java) but probably near or less than languages with more advanced typing systems like Haskell or Rust, but I'd really like to see something more comprehensive than a subjective opinion.
I got the impression that the bugs found were either not at all serious (e.g. throwing a typeerror on malformed input instead of some other nicer kind of error) or were in areas of the code not covered by tests.
Unfortunately the author does not rate them by severity.