Treat 0-length downloaded files as failure

Attempted workaround for https://gitlab.ssec.wisc.edu/cspp_geo/cspp-geo-aitf/-/issues/479

csppfetch/__init__.py

@@ -630,6 +630,16 @@ def download_all(url_to_dst, download_stats, do_download, timeout):
                     logging.debug(f"    {dst} removed")
             raise
 
+    # Attempted workaround for mysterious 0-length files
+    for url,dst in todo.items():
+        (path,file,atomic) = dst
+        size = os.path.getsize(path)
+        logging.debug(f"{path} is {size} bytes long");
+        if size == 0:
+            logging.warning(f"Downloaded file {path} is empty; it shouldn't be. Deleting it to prevent cascading failures. Other jobs running now may have problems.")
+            os.unlink(path)
+            raise Exception(f"Unexpected empty file: {path}")
+
 
 
 class CleaningStats: