I find the fastest way to introduce bugs into programs is to compile programs differently in development than in production. It also warps developer's perspectives of how their program performs. As they say at NASA, "Test what you fly, fly what you test."

That said, you can do this easily enough in Go. Define a package:

  package debug

  const Debug = true

  func Assert(cond bool, msg string) {
        if Debug && cond {
                panic(msg)
        }
  }

Have your build system generate the file that contains Debug = true. In optimization mode, make it Debug = false. As it is const, the compiler will propagate it, Assert will be inlined and the dead code removed. If you don't like relying on the compiler, have your code generator generate empty Assert functions. If you are working in a very bad code base that catches all panics, you'll need an extra 5 lines of code in the implementation of Assert, and your stack traces won't be pretty. (Roughly: put the condition check in a goroutine, block the Assert call on a channel signal from that goroutine.) I'd recommend the first project be to remove those panic catch-alls.

But really, all of this is only appropriate when you are far out in the weeds. Ship your program with those asserts. If they are too slow for production they are too slow for development.