Fix bytecode blowup due to nested nullable subexpressions.

This bug was discovered by the LLVM fuzzer.

Change-Id: I748a6ba1a7db4f9984acc7d354dfc6a662697714
Reviewed-on: https://code-review.googlesource.com/10891
Reviewed-by: Paul Wankadia <junyer@google.com>
4 files changed