[LLDB][NFC][Reliability] Fixes for int overflow and uninitialized state

Fixing potential int overflow and uninitialized variables.
These were found by Coverity static code inspection.

Differential Revision: https://reviews.llvm.org/D130795

GitOrigin-RevId: f7c961cc6ba71c9d1fb845807e31b3a278d13c2f
6 files changed