Sanity check the path before attempting to construct app

This reduce the number of concurrent tasks, at the cost of increased spawn latency

src/main.rs

@@ -67,14 +67,30 @@ fn get_dokku_root() -> Option<std::path::PathBuf> {
     None
 }
 
+fn osstring_starts_with(data: std::ffi::OsString, prefix: char) -> bool {
+    match data.into_string() {
+        Ok(s) => matches!(s.chars().next(), Some(c) if c == prefix),
+        Err(_) => false,
+    }
+}
+
 async fn hosts(State(state): State<AppState>) -> axum::Json<Vec<DokkuApp>> {
     let mut dir_entries = state.dokku_root.read_dir().await.unwrap();
 
     let mut join_set = JoinSet::new();
 
     while let Some(Ok(dir_entry)) = dir_entries.next().await {
+        // Skip hidden folders / files
+        if osstring_starts_with(dir_entry.file_name(), '.') {
+            continue;
+        }
+
         let path = dir_entry.path();
 
+        if !path.is_dir().await {
+            continue;
+        }
+
         join_set.spawn(DokkuApp::try_from_path(path));
     }