Fixed a few minor bugs found by fuzzing.

.bazelrc

diff --git a/.bazelrc b/.bazelrc
index df04df1..7b9da71 100644
--- a/.bazelrc
+++ b/.bazelrc
@@ -18,3 +18,5 @@
 build:analyzer --per_file_copt=json/parser@-fno-analyzer
 build:analyzer --per_file_copt=com_google_protobuf@-fno-analyzer
 build:analyzer --per_file_copt=com_github_google_benchmark@-fno-analyzer
+
+build:asan-fuzzer --copt=-fsanitize=address,fuzzer --linkopt=-fsanitize=address,fuzzer --define fuzz=true