update app.py

app.py

@@ -56,8 +56,13 @@ st.title("Sentinel Dataset")
 main_selection = st.selectbox("Select Sentinel Dataset Category", list(data.keys()))
 
 if main_selection:
-    sub_options = data[main_selection]["sub_options"]
-    sub_selection = st.selectbox("Select Specific Dataset ID", list(sub_options.keys()))
+    # Check if 'sub_options' exists in the selected main_selection
+    if "sub_options" in data[main_selection]:
+        sub_options = data[main_selection]["sub_options"]
+        sub_selection = st.selectbox("Select Specific Dataset ID", list(sub_options.keys()))
+    else:
+        st.error(f"No sub-options available for the selected dataset category: {main_selection}")
+        sub_options = None  # Set to None if no sub-options exist
 
 # Earth Engine Index Calculator Section
 st.header("Earth Engine Index Calculator")