Fix uninitialized memory read on broken files

oss-fuzz/10059
7 jobs for 10059 in 5 minutes and 59 seconds
Status Job ID Name Coverage
  Build
passed #6536443
build

00:05:50

passed #6536448
build_android

00:00:58

passed #6536444
build_clang_libcpp

00:05:59

passed #6536447
build_clazy

00:05:47

passed #6536446
build_mingw64_fedora

00:03:22

passed #6536445
build_ubuntu_16_04

00:03:25

passed #6536442
clang_format

00:01:28