Slow Cooker Hot Crab Dip Recipe

package (8 ounces) cream cheese, softened1/2 cup finely chopped sweet onion1/4 cup grated Parmesan cheese1/4 cup mayonnaise2 garlic cloves, minced2 teaspoons sugar1 can (6 ounces) crabmeat, drained, flaked and cartilage removedAssorted crackers