Correctly initialize config filename.

Author: zeyus

src/api_config.cpp

@@ -56,7 +56,7 @@ api_config::api_config() {
 	std::vector<std::string> filenames;
 
 	// NOLINTNEXTLINE(concurrency-mt-unsafe)
-	if (api_config_filename_ != "") {
+	if (!api_config_filename_.empty()) {
 		// if a config file name was set, use it if it is readable
 		if (file_is_readable(api_config_filename_)) {
 			filenames.insert(filenames.begin(), api_config_filename_);

src/api_config.h

@@ -236,7 +236,7 @@ class api_config {
 	 */
 	void load_from_file(const std::string &filename = std::string());
 
-	static std::string api_config_filename_ = "";
+	static std::string api_config_filename_;
 
 	// core parameters
 	bool allow_ipv6_, allow_ipv4_;
@@ -275,6 +275,10 @@ class api_config {
 	float smoothing_halftime_;
 	bool force_default_timestamps_;
 };
+
+// initialize configuration file name
+inline std::string api_config::api_config_filename_ = "";
+
 } // namespace lsl
 
 #endif