Restored the error reporting for the already closed cursor.

git-svn-id: svn+ssh://svn.code.sf.net/p/firebird/code/firebird/trunk@58999 65644016-39b1-43b1-bf79-96bc8fe82c15
Fixed CORE-4118: Expression index may be not used for derived fields or view fields.

git-svn-id: svn+ssh://svn.code.sf.net/p/firebird/code/firebird/trunk@59000 65644016-39b1-43b1-bf79-96bc8fe82c15