tour: Exercise Errors, missing explanation

[pr0gramista]

Context: https://tour.golang.org/methods/20

Note: a call to fmt.Sprint(e) inside the Error method will send the program into an infinite loop. You can avoid this by converting e first: fmt.Sprint(float64(e)). Why?

There is no explanation even though it is introduced.

[jjkavalam]

In fact, the statement does not seem to be true either.

https://go.dev/play/p/M7OT62bK-J7

package main

import (
	"fmt"
)

type ErrNegativeSqrt float64

func (e ErrNegativeSqrt) Error() string {
	return fmt.Sprintf("cannot Sqrt negative number: %f", e)
}

func Sqrt(x float64) (float64, error) {
	if x < 0 {
		return 0.0, ErrNegativeSqrt(x)
	}
	return 0, nil
}

func main() {
	fmt.Println(Sqrt(2))
	fmt.Println(Sqrt(-2))
}

The code above executes to completion:

0 <nil>
0 cannot Sqrt negative number: -2.000000

Program exited.

---

I believe, fmt.Sprint will use the String() method in preference to Error() method ?