Check if 'Unit' is NULL before trying to iterate over the diagnostics.
This obviates a null dereference that can occur when 'NumErrors'
is not zero.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@97849 91177308-0d34-0410-b5e6-96231b3b80d8
1 file changed