[core] Coverity fixes

[core] Coverity fixes

* [core] Coverity 1518099, 1518097, 1518098 (Unchecked return value from library)

* [core] Coverity 1468551 Unchecked return value

* [core] Coverity 1468293 Unchecked return value

* [core] Coverity 1468274 Explicit null dereferenced

* [core] Coverity 1395588 Unchecked return value

* [core] Coverity 1395515 Logically dead code

* [core] Coverity 1364984 Result is not floating-point

* [core] Coverity 1395554, 1468440 Dereference before null check

* [core] Coverity 1024487 Dereference after null check

* [core] Coverity 1024872 Unchecked return value

* [core] Coverity 1025822 Unchecked return value

* [core] Coverity 1025823 Unchecked return value

* [core] Coverity 1087637, 1346467, 1087638 Unchecked return value

* [core] Coverity 1107607 Unchecked return value

* [core] Coverity 1210777 Unchecked return value

* [core] Coverity 1227670 Dereference before null check

* [core] Coverity 1024551 Logically dead code

* [core] Coverity 1024560 Logically dead code

* [core] Coverity 1024664 Operands don't affect result

* [core] Coverity 1364957 Dereference after null check

* [core] Coverity 1395572 Logically dead code

* [core] Coverity 1412459 Unchecked return value

* [core] Coverity 1412490 Unchecked return value

* [core] Coverity 1395515/2 Logically dead code

* [core] Coverity cleanup