Rule reminder
A left dislocation sentence is ungrammatical or unnatural if: (1) the resumptive clitic is missing, (2) the clitic has the wrong gender or number, (3) the wrong type of clitic is used (e.g., direct instead of indirect). Every dislocated argument must be resumed by the appropriate clitic inside the clause.
Which error is in: 'La torta, ho mangiato tutta.'?