Don't remove existing logger from registry in set_default_logger

src/details/registry.cpp

@@ -125,10 +125,6 @@ namespace spdlog {
 // default logger is stored in default_logger_ (for faster retrieval) and in the loggers_ map.
         void registry::set_default_logger(std::shared_ptr<logger> new_default_logger) {
             std::lock_guard<std::mutex> lock(logger_map_mutex_);
-            // remove previous default logger from the map
-            if (default_logger_ != nullptr) {
-                loggers_.erase(default_logger_->name());
-            }
             if (new_default_logger != nullptr) {
                 loggers_[new_default_logger->name()] = new_default_logger;
             }