Merge branch '1-cast-to-String-before-stripping' into...

Merge branch '1-cast-to-String-before-stripping' into '1-crash-in-a-test-file-with-non-empty-z-column'

Resolve "Crash in a test file with non-empty Z column" in patch branch

See merge request !3

conML/ports/source_adapter.py

@@ -297,7 +297,7 @@ class PandasBlock:
                 True, if labeled.
 
         """
-        values_empty = self.df["Z"].iloc[0].strip('""') == ''
+        values_empty = str(self.df["Z"].iloc[0]).strip('""') == ''
         values_unique = self.df["Z"].nunique() == 1
         if values_empty and values_unique:
             return False