Add returning of error in case if artifact is not found in github release info (#110)

Author: denis256

main.go

@@ -416,7 +416,7 @@ func downloadReleaseAssets(logger *logrus.Logger, assetRegex string, destPath st
 
 	release, releaseInfoErr := GetGitHubReleaseInfo(githubRepo, tag)
 	if releaseInfoErr != nil {
-		return nil, err
+		return nil, releaseInfoErr
 	}
 
 	assets, err := findAssetsInRelease(assetRegex, release)

main_test.go

@@ -2,6 +2,7 @@ package main
 
 import (
 	"fmt"
+	"github.com/stretchr/testify/assert"
 	"os"
 	"testing"
 )
@@ -95,3 +96,20 @@ func TestInvalidReleaseAssetsRegex(t *testing.T) {
 		t.Fatalf("Expected error for invalid regex")
 	}
 }
+
+func TestInvalidReleaseAssetTag(t *testing.T) {
+	tmpDir := mkTempDir(t)
+	logger := GetProjectLogger()
+	testInst := GitHubInstance{
+		BaseUrl: "github.com",
+		ApiUrl:  "api.github.com",
+	}
+
+	githubRepo, err := ParseUrlIntoGitHubRepo(SAMPLE_RELEASE_ASSET_GITHUB_REPO_URL, "", testInst)
+	if err != nil {
+		t.Fatalf("Failed to parse sample release asset GitHub URL into Fetch GitHubRepo struct: %s", err)
+	}
+
+	_, fetchErr := downloadReleaseAssets(logger, SAMPLE_RELEASE_ASSET_REGEX, tmpDir, githubRepo, "6.6.6", false)
+	assert.Error(t, fetchErr)
+}