CMake Error at /opt/ros/melodic/share/genmsg/cmake/genmsg-extras.cmake:94 (message):

问题遇到的现象和发生背景 ，在catkin_ws中运行catkin_make所出现的问题
问题相关代码 catkin_make

运行结果及报错内容 CMake Error at /opt/ros/melodic/share/genmsg/cmake/genmsg-extras.cmake:94 (message):
add_message_files() directory not found: /home/melodic/catkin_ws/src/msg
Call Stack (most recent call first):
CMakeLists.txt:77 (add_message_files)

-- Configuring incomplete, errors occurred!
See also "/home/melodic/catkin_ws/build/CMakeFiles/CMakeOutput.log".
See also "/home/melodic/catkin_ws/build/CMakeFiles/CMakeError.log".
Invoking "cmake" failed