Fix an error where time travelling with no chrono tasks would cause a…

… segmentation fault (#105)

When time travelling in NEAREST mode with no chrono tasks, the code
would try to dereference an empty list. Fix this to ensure it works when
no chrono tasks are present

src/extension/ChronoController.hpp

@@ -116,11 +116,10 @@ namespace extension {
 
                     } break;
                     case message::TimeTravel::Action::NEAREST: {
-                        auto next_task =
-                            std::min_element(tasks.begin(), tasks.end(), [](const ChronoTask& a, const ChronoTask& b) {
-                                return a.time < b.time;
-                            });
-                        clock::set_clock(std::min(next_task->time, travel.target), travel.rtf);
+                        const clock::time_point nearest =
+                            tasks.empty() ? travel.target
+                                          : std::min(travel.target, std::min_element(tasks.begin(), tasks.end())->time);
+                        clock::set_clock(nearest, travel.rtf);
                     } break;
                 }