master a7291a9: Fix a segfault in daemon mode Emacs when detaching an X session

[Lars Ingebrigtsen]

branch: master
commit a7291a9fb979e117c3286d3cfa6d0d15557edace
Author: Doug Gilmore <dougjgilmore@gmail.com>
Commit: Lars Ingebrigtsen <larsi@gnus.org>

    Fix a segfault in daemon mode Emacs when detaching an X session
    
    * src/xterm.c (x_uncatch_errors): Add a sanity check for
    x_error_message (bug#23939).
---
 src/xterm.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/src/xterm.c b/src/xterm.c
index 2a99c46..2e0407a 100644
--- a/src/xterm.c
+++ b/src/xterm.c
@@ -9921,6 +9921,13 @@ x_uncatch_errors (void)
 {
   struct x_error_message_stack *tmp;
 
+  /* In rare situations when running Emacs run in daemon mode,
+     shutting down an emacsclient via delete-frame can cause
+     x_uncatch_errors to be called when x_error_message is set to
+     NULL.  */
+  if (x_error_message == NULL)
+    return;
+
   block_input ();
 
   /* The display may have been closed before this function is called.