NULL is returned when bool is expected

Build breaks:
/usr/ports/science/salome-kernel/work/salome-kernel-V9_11_0/src/SALOMEDSImpl/SALOMEDSImpl_Study.cxx:215:14: error: cannot initialize return object of type ‘bool’ with an rvalue of type ‘std::nullptr_t’
return NULL;
^~~~
/usr/include/sys/_null.h:37:14: note: expanded from macro ‘NULL’
#define NULL nullptr
^~~~~~~
/usr/ports/science/salome-kernel/work/salome-kernel-V9_11_0/src/SALOMEDSImpl/SALOMEDSImpl_Study.cxx:237:12: error: cannot initialize return object of type ‘bool’ with an rvalue of type ‘std::nullptr_t’
return NULL;
^~~~
/usr/include/sys/_null.h:37:14: note: expanded from macro ‘NULL’
#define NULL nullptr
^~~~~~~
2 errors generated.

NULL is the same as nullptr and it can’t be returned as the boolean ‘false’ value.