error handling enhancements

data/error.go

@@ -5,11 +5,17 @@ import (
 	"os/exec"
 )
 
-func getErrorMessage(err *exec.ExitError) string {
+func getErrorMessage(err error) string {
-	stderr := string(err.Stderr)
+
-	if len(stderr) == 0 {
+	exitErr, ok := err.(*exec.ExitError)
-		return err.Error()
+	message := err.Error()
-	} else {
+
-		return fmt.Sprintf("%.200s", stderr)
+	if ok {
+		stderr := string(exitErr.Stderr)
+		if len(stderr) != 0 {
+			message = fmt.Sprintf("%.200s", stderr)
+		}
 	}
+
+	return message
 }

data/sampler.go

@@ -2,7 +2,6 @@ package data
 
 import (
 	"github.com/sqshq/sampler/config"
-	"os/exec"
 	"time"
 )
 
@@ -57,7 +56,7 @@ func (s *Sampler) sample(item Item, options config.Options) {
 	} else {
 		s.consumer.AlertChannel <- &Alert{
 			Title: "SAMPLING FAILURE",
-			Text:  getErrorMessage(err.(*exec.ExitError)),
+			Text:  getErrorMessage(err),
 			Color: item.Color,
 		}
 	}

data/trigger.go

@@ -107,7 +107,7 @@ func (t *Trigger) evaluate(sample *Sample) bool {
 	if err != nil {
 		t.consumer.AlertChannel <- &Alert{
 			Title: "TRIGGER CONDITION FAILURE",
-			Text:  getErrorMessage(err.(*exec.ExitError)),
+			Text:  getErrorMessage(err),
 		}
 	}