src/os/unix/ngx_readv_chain.c:204: error: Null Dereference
  pointer `iov` last assigned on line 191 could be null and is dereferenced at line 204, column 13.

src/os/unix/ngx_readv_chain.c:180:1: start of procedure ngx_readv_chain()
178. #else /* ! NGX_HAVE_KQUEUE */
179. 
180. ssize_t
     ^
181. ngx_readv_chain(ngx_connection_t *c, ngx_chain_t *chain)
182. {

src/os/unix/ngx_readv_chain.c:190:5: 
188.     struct iovec  *iov, iovs[NGX_IOVS];
189. 
190.     prev = NULL;
         ^
191.     iov = NULL;
192.     size = 0;

src/os/unix/ngx_readv_chain.c:191:5: 
189. 
190.     prev = NULL;
191.     iov = NULL;
         ^
192.     size = 0;
193. 

src/os/unix/ngx_readv_chain.c:192:5: 
190.     prev = NULL;
191.     iov = NULL;
192.     size = 0;
         ^
193. 
194.     vec.elts = iovs;

src/os/unix/ngx_readv_chain.c:194:5: 
192.     size = 0;
193. 
194.     vec.elts = iovs;
         ^
195.     vec.nelts = 0;
196.     vec.size = sizeof(struct iovec);

src/os/unix/ngx_readv_chain.c:195:5: 
193. 
194.     vec.elts = iovs;
195.     vec.nelts = 0;
         ^
196.     vec.size = sizeof(struct iovec);
197.     vec.nalloc = NGX_IOVS;

src/os/unix/ngx_readv_chain.c:196:5: 
194.     vec.elts = iovs;
195.     vec.nelts = 0;
196.     vec.size = sizeof(struct iovec);
         ^
197.     vec.nalloc = NGX_IOVS;
198.     vec.pool = c->pool;

src/os/unix/ngx_readv_chain.c:197:5: 
195.     vec.nelts = 0;
196.     vec.size = sizeof(struct iovec);
197.     vec.nalloc = NGX_IOVS;
         ^
198.     vec.pool = c->pool;
199. 

src/os/unix/ngx_readv_chain.c:198:5: 
196.     vec.size = sizeof(struct iovec);
197.     vec.nalloc = NGX_IOVS;
198.     vec.pool = c->pool;
         ^
199. 
200.     /* coalesce the neighbouring bufs */

src/os/unix/ngx_readv_chain.c:202:12: Loop condition is true. Entering loop body
200.     /* coalesce the neighbouring bufs */
201. 
202.     while (chain) {
                ^
203.         if (prev == chain->buf->last) {
204.             iov->iov_len += chain->buf->end - chain->buf->last;

src/os/unix/ngx_readv_chain.c:203:13: Taking true branch
201. 
202.     while (chain) {
203.         if (prev == chain->buf->last) {
                 ^
204.             iov->iov_len += chain->buf->end - chain->buf->last;
205. 

src/os/unix/ngx_readv_chain.c:204:13: 
202.     while (chain) {
203.         if (prev == chain->buf->last) {
204.             iov->iov_len += chain->buf->end - chain->buf->last;
                 ^
205. 
206.         } else {
