Remove unnecessary null pointer checks (ASWF issue #257)

[epowers]

Fix remove unnecessary null pointer checks, issue #257.

There only appeared to be one obvious case left.

Code search process:

grep -C 3 delete .

... then look for if statements, in C-like code, conditioned on the same variable, and no other obvious purpose that required the if statement.

See:

https://github.com/AcademySoftwareFoundation/openvdb/issues/257

[linux-foundation-easycla[bot]]

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• :white_check_mark: login: epowers / name: Eric Powers (135616d1773a906861048e4ef11c67d03ab90948)

[epowers]

CLA Not Signed...

working this internally...