clang-tidy: Enable bugprone-unchecked-optional

Modified code to address issues flagged by
bugprone-unchecked-optional-access check.

Tested: Build and unit tests passed successfully.

Change-Id: Icd445afaf827f7c346e44dfe3ce9ba98374e176a
Signed-off-by: Jayanth Othayoth <ojayanth@gmail.com>
diff --git a/.clang-tidy b/.clang-tidy
index 502f430..0dc7755 100644
--- a/.clang-tidy
+++ b/.clang-tidy
@@ -66,6 +66,7 @@
 bugprone-terminating-continue,
 bugprone-throw-keyword-missing,
 bugprone-too-small-loop-variable,
+bugprone-unchecked-optional-access,
 bugprone-undefined-memory-manipulation,
 bugprone-undelegated-constructor,
 bugprone-unhandled-exception-at-new,