replace AbortWithError calls by custom function that sets the content type correctly

api/packages.go

@@ -9,7 +9,7 @@ func apiPackagesShow(c *gin.Context) {
 	collectionFactory := context.NewCollectionFactory()
 	p, err := collectionFactory.PackageCollection().ByKey([]byte(c.Params.ByName("key")))
 	if err != nil {
-		c.AbortWithError(404, err)
+		AbortWithJSONError(c, 404, err)
 		return
 	}