Fix direct execution of AppImages

Fetch a list of all child PIDs before forwarding the termination signal.
Once the main process is terminated, forward that term signal to all found children also (if they are still running)

overlay/usr/bin/sunshine-run

@@ -24,8 +24,25 @@ echo
 # Trap SIGINT, SIGQUIT, SIGHUP, SIGTERM to forward signals to the child process
 _term() {
     if [ -n "${proc_pid}" ]; then
-        echo "  - Forwarding signal $1 to process ${proc_pid}"
-        kill -s "${1}" "${proc_pid}"
+        # Read all child processes of proc_pid first
+        child_pids=$(pgrep -P $proc_pid)
+        # Forward the signal proc_pid
+        echo "  - Checking for status of main process ${proc_pid}"
+        if kill -0 "${proc_pid}" 2>/dev/null; then
+            echo "      - Forwarding signal $1 to process ${proc_pid}"
+            kill -s "${1}" "${proc_pid}"
+        else
+            echo "      - Process ${proc_pid} is already stopped. Nothing to do here."
+        fi
+        for child_pid in ${child_pids:-}; do
+            echo "  - Checking for status of child process ${child_pid}"
+            if kill -0 "${child_pid}" 2>/dev/null; then
+                echo "      - Forwarding signal $1 to process ${child_pid}"
+                kill -s "${1}" "${child_pid}"
+            else
+                echo "      - Process ${child_pid} is already stopped. Nothing to do here."
+            fi
+        done
     fi
 }
 trap '_term INT' SIGINT