fail in no data

src/data.py

@@ -19,8 +19,14 @@ def load_from_thredds(
 ) -> (pd.DataFrame, dict[int, str]):  # type: ignore
     """
     Load multiple netCDF files from a THREDS TDS into a single DataFrame.
+
+    Raises:
+        ValueError: If 'ACN' not found in dataset.
+        ValueError: If no datasets are found.
     """
+
     log.debug("begin load data from THREDDS...")
+
     dataframes = []
     airports = {}
 
@@ -54,7 +60,11 @@ def load_from_thredds(
 
         dataframes.append(df)
 
+    if len(dataframes) == 0:
+        raise ValueError("No datasets found!")
+
     log.debug("Data loaded from THREDDS successfully")
+
     return (pd.concat(dataframes), airports)
 
 
@@ -63,6 +73,10 @@ def load_from_disk(
 ) -> (pd.DataFrame, dict[int, str]):  # type: ignore
     """
     Load multiple netCDF files into a single DataFrame.
+
+    Raises:
+        ValueError: If 'ACN' not found in dataset.
+        ValueError: If no datasets are found.
     """
     dataframes = []
     airports = {}
@@ -99,5 +113,9 @@ def load_from_disk(
 
         dataframes.append(df)
 
+    if len(dataframes) == 0:
+        raise ValueError("No datasets found!")
+
     log.info("Data loaded from disk successfully")
+
     return (pd.concat(dataframes), airports)