grpc: Heap-buffer-overflow in internal_add_error

Detailed report: https://oss-fuzz.com/testcase?key=6312731374256128 Project: grpc Fuzzer: aflgrpcserverfuzzer Fuzz target binary: serverfuzzer Job Type: aflasangrpc Platform Id: linux Crash Type: Heap-buffer-overflow WRITE 1 Crash Address: 0x616000000a48 Crash State: internaladderror...