Case T-108/16: Judgment of the General Court of 15 March 2018 — Naviera Armas v Commission (State aid — Conditions of use of the Puerto Las Nieves port infrastructure by a shipping company — Exclusive use of infrastructures financed by public funds, without a concession contract — Partial exoneration of payment of port dues — Complaint lodged by a competitor — Decision finding no State aid at the end of the preliminary investigation procedure — Serious difficulties in the examination of the measures concerned — Developments in the situation during the administrative procedure — Concept of advantage granted by means of State resources — Errors of assessment of the facts and errors of law — Decision of a national court suspending the effects of a tendering procedure — Requirement of diligent and impartial examination of the complaint)