[Core] Coverity fixes

[Core] Coverity fixes

* [core] coverity CID 1320751 (Dereference before null check)

* [core] coverity CID 1294546 (Unchecked return value)

* [core] coverity CID 1227661 (Logically dead code)

* [core] coverity CID 1227656 (Logically dead code)

* [core] coverity CID 1060948 (Explicit null dereferenced)

* [core] coverity CID 1346465 (Unchecked return value)

* [core] coverity CID 1364953 (Logically dead code)

* [core] coverity CID 1468210 (Dereference before null check)

* [core] coverity CID 1468546 (Dereference before null check)

* [core] coverity CID 1468342 (Dereference before null check)