Fix issue with empty links in banners

src/data/config.rs

@@ -195,7 +195,11 @@ impl Config {
                     .collect(),
                 link: parsed_banner["link"].as_str()
                     .map(str::to_string)
-                    .map(Self::parse_string_val),
+                    .map(Self::parse_string_val)
+                    .and_then(|s| match s.is_empty() {
+                        true => None,
+                        false => Some(s)
+                    }),
             })
         };