CMake Error at BadSHELL_PATH.cmake:[0-9]+ \(add_custom_target\):
  Error evaluating generator expression:

    \$<SHELL_PATH:>

  "" is not an absolute path.
Call Stack \(most recent call first\):
  CMakeLists.txt:3 \(include\)
+
CMake Error at BadSHELL_PATH.cmake:[0-9]+ \(add_custom_target\):
  Error evaluating generator expression:

    \$<SHELL_PATH:Relative/Path>

  "Relative/Path" is not an absolute path.
Call Stack \(most recent call first\):
  CMakeLists.txt:3 \(include\)
+
CMake Error at BadSHELL_PATH.cmake:[0-9]+ \(add_custom_target\):
  Error evaluating generator expression:

    \$<SHELL_PATH:;>

  "" is not an absolute path.
Call Stack \(most recent call first\):
  CMakeLists.txt:3 \(include\)