make sure polygon is valid and not empty, otherwise, raise an error

src/rtc/h5_prep.py

@@ -154,10 +154,15 @@ def get_polygon_wkt(burst_in: Sentinel1BurstSlc):
     '''
 
     if len(burst_in.border) == 1:
-        geometry_polygon = burst_in.border[0]
+        geometry_polygon = shapely.geometry.Polygon(burst_in.border[0])
     else:
         geometry_polygon = shapely.geometry.MultiPolygon(burst_in.border)
-
+    if geometry_polygon.is_empty:
+        error_msg = f'empty bouding polygon for burst ID {burst_in.burst_id}'
+        raise RuntimeError(error_msg)
+    if not geometry_polygon.is_valid:
+        error_msg = f'invalid bounding polygon for burst ID {burst_in.burst_id}'
+        raise RuntimeError(error_msg)
     return geometry_polygon.wkt