whoops: fix build on linux

Author: jknack

jooby-whoops/src/main/java/org/jooby/whoops/Whoops.java

@@ -344,8 +344,8 @@ static Map<String, Object> frame(final ClassLoader loader, final SourceLocator l
         .put("lineNumber", line)
         .put("lineStart", lineStart + 1)
         .put("lineNth", lineNth)
-        .put("location", clazz.map(Whoops::locationOf)
-            .orElse(new File(filename).getParent()))
+        .put("location", Optional.ofNullable(clazz.map(Whoops::locationOf)
+            .orElse(new File(filename).getParent())).orElse(filename))
         .put("source", source.source(range[0], range[1]))
         .put("open", openWith.apply(filePath, line))
         .put("type", clazz.map(c -> c.getSimpleName()).orElse(new File(filename).getName()))