[core] Coverity fixes

[core] Coverity fixes

* [core] Coverity CID 1024233 (Dereference before null check)

* [core] Coverity CID 1024239 (Dereference before null check)

* [core] Coverity CID 1024242 (Dereference before null check)

* [core] Coverity CID 1024243 (Dereference before null check)

* [core] Coverity CID 1024453 (Dereference before null check)

* [core] Coverity CID 1024554 (Logically dead code)

* [core] Coverity CID 1024868 (unchecked return value from library)

* [core] Coverity CID 1024869 (unchecked return value from library)

* [core] Coverity CID 1468281 (Dereference before null check)

* [core] Coverity CID 1024238 (Dereference before null check)

* [core] Coverity CID 1468621 (Copy into fixed size buffer)

* [core] Coverity CID 1024871 (Unchecked return value)