[system.data] Appended the fix to correct the whitespace Expression and argument checking
- Whitespace Espressions:
-- if a column expression is a pure whitespace, use an empty string instead
-- if a column expression is surrounded by whitespace, preserve whitespace
-- if a column expression is null/empty, use an empty string
- Get a row's column value:
-- make sure we throw exceptions if the column we are looking at is null
-- make sure we throw exceptions if we can't find the column with the provided name