check that the file could be read

formats/geotiff_format.py

@@ -7,6 +7,10 @@ import os
 def is_geotiff(resource, file_name):
     dataset = gdal.Open(file_name)
 
+    if not dataset:
+        resource["error"] = f"could not read file {file_name}"
+        return False
+
     geotransform = dataset.GetGeoTransform()
     default_transform = (0.0, 1.0, 0.0, 0.0, 0.0, 1.0)