REFAC: add warning messages when geoid or dem cannot be opened and don't try...

REFAC: add warning messages when geoid or dem cannot be opened and don't try to use a null dataset to create the shifted dataset when the geoid cannot be opened
19 jobs for !881 with 2221_clean_of_elevation_parameters in 83 minutes and 24 seconds (queued for 3 seconds)
detached
Status Name Job ID Coverage
  Precheck
passed fast-build #54925

00:18:54

passed legal-check #54926

00:02:44

 
  Prepare
passed centos-xdk-prepare #54928

00:01:32

passed macos-xdk-prepare #54929
macos

00:00:39

passed ubuntu-xdk-prepare #54927

00:00:49

passed windows-10-prepare #54930
windows10

00:00:26

 
  Build
passed centos-xdk-build #54932

00:28:39

passed macos-xdk-build #54933
macos

00:13:23

passed ubuntu-xdk-build-doc #54931

00:33:41

passed ubuntu-xdk-qa-code-coverage #54935

00:50:58

passed ubuntu-xdk-qa-static-analysis #54936

00:57:53

passed windows-10-build #54934
windows10

00:23:49

 
  Report
passed ubuntu-xdk-report #54937

00:05:42

 
  External
passed cdash:centos-7.9.2009-gcc

passed cdash:macos-10.14.6-clang

passed cdash:ubuntu-18.04-fast

passed cdash:ubuntu-18.04-llvm-qa

passed cdash:ubuntu-18.04-llvm-xdk

passed cdash:windows-10-x64-vc14.29