Fix render pass example on ogre2

[iche033]

Signed-off-by: Ian Chen ichen@osrfoundation.org

🦟 Bug fix

Summary

Running the render_pass example with ogre2 currently results in a crash because it tries to load the distortion render pass which has not been ported to ogre2 implementation yet.

This PR adds a check to make sure the render pass is not null before adding it to the render pass system.

to test, build and run the render_pass example:

./render_pass ogre2

Checklist

• Signed all commits for DCO
• Added tests
• Updated documentation (as needed)
• Updated migration guide (as needed)
• codecheck passed (See contributing)
• All tests passed (See test coverage)
• While waiting for a review on your PR, please help review another open pull request to support the maintainers

Note to maintainers: Remember to use Squash-Merge and edit the commit message to match the pull request summary while retaining Signed-off-by messages.

[codecov]

Codecov Report

Merging #576 (129b247) into ign-rendering6 (dd8b465) will not change coverage.
The diff coverage is n/a.

❗ Current head 129b247 differs from pull request most recent head 2020b0b. Consider uploading reports for the commit 2020b0b to get more accurate results

@@               Coverage Diff               @@
##           ign-rendering6     #576   +/-   ##
===============================================
  Coverage           54.35%   54.35%           
===============================================
  Files                 198      198           
  Lines               20170    20170           
===============================================
  Hits                10963    10963           
  Misses               9207     9207           

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[ahcorde]

@osrf-jenkins retest this please

[ahcorde]

@osrf-jenkins retest this please