fail on image not found without panic; add extra chmod case to test dockerfile

.data/Dockerfile

@@ -2,6 +2,7 @@ FROM alpine:latest
 ADD README.md /somefile.txt
 RUN mkdir /root/example
 RUN cp /somefile.txt /root/example/somefile1.txt
+RUN chmod 444 /root/example/somefile1.txt
 RUN cp /somefile.txt /root/example/somefile2.txt
 RUN cp /somefile.txt /root/example/somefile3.txt
 RUN mv /root/example/somefile3.txt /root/saved.txt

image/image.go

@@ -268,7 +268,10 @@ func getImageReader(imageID string) (io.ReadCloser, int64) {
 	fmt.Println("  Fetching metadata...")
 
 	result, _, err := dockerClient.ImageInspectWithRaw(ctx, imageID)
-	check(err)
+	if err != nil {
+		fmt.Println(err.Error())
+		utils.Exit(1)
+	}
 	totalSize := result.Size
 
 	fmt.Println("  Fetching image...")