Weird behavior around value method errors

main.go

package main

import (
	"log"
)

type ErrorType struct {
}

func (e ErrorType) Error() string {
	return "error"
}

func getNilError() *ErrorType {
	return nil
}

func main() {
	var err error
	err = getNilError()
	log.Printf("Pointer: %p", err)

	if err != nil {
		log.Println("Received:", err.Error())
	} else {
		log.Println("All fine")
	}
}

output.txt

2015/05/05 13:07:31 Pointer: 0x0
	panic: value method main.ErrorType.Error called using nil *ErrorType pointer
	
	goroutine 1 [running]:
	main.(*ErrorType).Error(0x0, 0xb, 0xc20802df48)
		<autogenerated>:1 +0x82
	main.main()
		[ ..REDACTED.. ]/main.go:24 +0x159
	
	goroutine 2 [runnable]:
	runtime.forcegchelper()
		/usr/local/go/src/runtime/proc.go:90
	runtime.goexit()
		/usr/local/go/src/runtime/asm_amd64.s:2232 +0x1
	
	goroutine 3 [runnable]:
	runtime.bgsweep()
		/usr/local/go/src/runtime/mgc0.go:82
	runtime.goexit()
		/usr/local/go/src/runtime/asm_amd64.s:2232 +0x1
	
	goroutine 4 [runnable]:
	runtime.runfinq()
		/usr/local/go/src/runtime/malloc.go:712
	runtime.goexit()
		/usr/local/go/src/runtime/asm_amd64.s:2232 +0x1