Fixing ignored errors from fizz exec() (#71)

* make sure that command failures with Exec() fail their migrations

* remove unused return error

fizz/bubbler_test.go

@@ -13,7 +13,6 @@ func Test_Exec(t *testing.T) {
 	b := NewBubbler(nil)
 	f := fizzer{b}
 	bb := &bytes.Buffer{}
-	err := f.Exec(bb).(func(string) error)("echo hello")
-	r.NoError(err)
+	f.Exec(bb).(func(string))("echo hello")
 	r.Equal("hello\n", bb.String())
 }

fizz/fizz.go

@@ -1,6 +1,7 @@
 package fizz
 
 import (
+	"fmt"
 	"io"
 	"io/ioutil"
 	"log"
@@ -24,13 +25,16 @@ func (f fizzer) add(s string, err error) error {
 }
 
 func (f fizzer) Exec(out io.Writer) interface{} {
-	return func(s string) error {
+	return func(s string) {
 		args := strings.Split(s, " ")
 		cmd := exec.Command(args[0], args[1:]...)
 		cmd.Stdin = os.Stdin
 		cmd.Stdout = out
 		cmd.Stderr = os.Stderr
-		return cmd.Run()
+		err := cmd.Run()
+		if err != nil {
+			panic(fmt.Sprintf("error executing command: %s", s))
+		}
 	}
 }