[FIX] attachment_preview: fix get_binary_extension

attachment_preview/models/ir_attachment.py

@@ -41,6 +41,8 @@ class IrAttachment(models.Model):
         ids_to_browse = [_id for _id in ids_to_browse if _id not in result]
         for this in self.env[model].with_context(bin_size=True).browse(ids_to_browse):
             result[this.id] = False
+            if not this[binary_field]:
+                continue
             try:
                 import magic