Add warnings for invalid fast-forward settings.

Fixes https://github.com/dcs-liberation/dcs_liberation/issues/2739.

qt_ui/widgets/QTopPanel.py

@@ -1,3 +1,4 @@
+import textwrap
 from datetime import datetime
 from typing import List, Optional, Callable
 
@@ -246,6 +247,50 @@ class QTopPanel(QFrame):
         mbox.exec_()
         return True
 
+    def check_valid_autoresolve_settings(self) -> bool:
+        if not self.game.settings.fast_forward_to_first_contact:
+            return True
+
+        if not self.game.settings.auto_resolve_combat:
+            return True
+
+        has_clients = self.ato_has_clients()
+        if (
+            has_clients
+            and self.game.settings.player_mission_interrupts_sim_at is not None
+        ):
+            return True
+
+        if has_clients:
+            message = textwrap.dedent(
+                """\
+                You have enabled settings to fast forward and to auto-resolve combat,
+                but have not selected any interrupt condition. Fast forward will never
+                stop with your current settings. To use auto- resolve, you must choose a
+                "Player missions interrupt fast forward" setting other than "Never".
+                """
+            )
+        else:
+            message = textwrap.dedent(
+                """\
+                You have enabled settings to fast forward and to auto-resolve combat,
+                but have no players. Fast forward will never stop with your current
+                settings. Auto-resolve and fast forward cannot be used without player
+                flights and a "Player missions interrupt fast forward" setting other
+                than "Never".
+                """
+            )
+
+        mbox = QMessageBox(
+            QMessageBox.Icon.Critical,
+            "Incompatible fast-forward settings",
+            message,
+            parent=self,
+        )
+        mbox.setEscapeButton(mbox.addButton(QMessageBox.StandardButton.Close))
+        mbox.exec()
+        return False
+
     def launch_mission(self):
         """Finishes planning and waits for mission completion."""
         if not self.ato_has_clients() and not self.confirm_no_client_launch():
@@ -261,6 +306,9 @@ class QTopPanel(QFrame):
             if not self.confirm_negative_start_time(negative_starts):
                 return
 
+        if not self.check_valid_autoresolve_settings():
+            return
+
         if self.game.settings.fast_forward_to_first_contact:
             with logged_duration("Simulating to first contact"):
                 self.sim_controller.run_to_first_contact()