utils: readCompleteFile(): Fix error string which is too generic without context

utils.cpp

@@ -136,11 +136,10 @@ std::string utils::getenv(const std::string &key)
 
 std::string utils::readCompleteFile(std::string_view filepath)
 {
-
 	std::fstream stream(std::string{filepath});
 	if(!stream.is_open())
 	{
-		throw std::runtime_error("stream is not open");
+		throw std::runtime_error("utils::readCompleteFile(): stream is not open");
 	}
 	std::stringstream ss;
 	ss << stream.rdbuf();