Don't clame date error for a block that doesn't even have a date.

diff --git a/src/ledgplom/ledger.py b/src/ledgplom/ledger.py
index cae1ac163ce94db910b1694942df93762dd531fb..a400cccdb8afcaa4de5346c23256b6bbdc849822 100644 (file)
--- a/src/ledgplom/ledger.py
+++ b/src/ledgplom/ledger.py
@@ -513,7 +513,7 @@ class _DatBlock(_LinesBlock, _LedgerNode):
     @property
     def date_error(self) -> str:
         'If not empty, notify about .date not matching position in chain.'
-        if self.prev and self.prev.date > self.date:
+        if self.date and self.prev and self.prev.date > self.date:
             return 'date < previous date'
         return ''