Don't crash if no asynchronous process has been created yet.scratch/sigchld-fd

* src/process.c (wait_reading_process_output): Allow
child_signal_read_fd < 0.

1 files changed, 2 insertions, 2 deletions

diff --git a/src/process.c b/src/process.c
index 474c87089e0..aca87f8ed35 100644
--- a/src/process.c
+++ b/src/process.c
@@ -5413,9 +5413,9 @@ wait_reading_process_output (intmax_t time_limit, int nsecs, int read_kbd,
          an asynchronous process.  Otherwise this might deadlock if we
          receive a SIGCHLD during `pselect'.  */
       int child_fd = child_signal_read_fd;
-      eassert (0 <= child_fd);
       eassert (child_fd < FD_SETSIZE);
-      FD_SET (child_fd, &Available);
+      if (0 <= child_fd)
+        FD_SET (child_fd, &Available);
 
       /* If frame size has changed or the window is newly mapped,
          redisplay now, before we start to wait.  There is a race