Harden cthulhu's terminal release code.

src/cthulhu/input_event_manager.py

@@ -477,28 +477,49 @@ class InputEventManager:
             return None
 
         self._log_active_x11_window_for_xterm_check(window)
+        sawIdentifier = False
         for attrName in ("get_class_group_name", "get_class_instance_name", "get_name"):
-            if self._identifier_is_xterm(self._safe_call(window, attrName)):
+            value = self._safe_call(window, attrName)
+            if self._identifier_is_xterm(value):
                 return True
+            if isinstance(value, str) and value.strip():
+                sawIdentifier = True
 
         classGroup = self._safe_call(window, "get_class_group")
         if classGroup is not None:
 
             for attrName in ("get_name", "get_res_class"):
-                if self._identifier_is_xterm(self._safe_call(classGroup, attrName)):
+                value = self._safe_call(classGroup, attrName)
+                if self._identifier_is_xterm(value):
                     return True
+                if isinstance(value, str) and value.strip():
+                    sawIdentifier = True
 
         try:
             pid = int(window.get_pid())
         except Exception:
             pid = -1
         if pid < 1:
+            if not sawIdentifier:
+                msg = (
+                    "INPUT EVENT MANAGER: XTerm matcher cannot identify active X11 window; "
+                    "no usable identifiers or pid."
+                )
+                debug.print_message(debug.LEVEL_INFO, msg, True)
+                return None
             return False
 
         try:
             with open(f"/proc/{pid}/cmdline", "rb") as cmdlineFile:
                 executable = cmdlineFile.read().split(b"\0", 1)[0].decode(errors="ignore")
         except OSError:
+            if not sawIdentifier:
+                msg = (
+                    "INPUT EVENT MANAGER: XTerm matcher cannot identify active X11 window; "
+                    "pid disappeared before cmdline lookup."
+                )
+                debug.print_message(debug.LEVEL_INFO, msg, True)
+                return None
             return False
 
         return self._identifier_is_xterm(executable)
@@ -635,15 +656,15 @@ class InputEventManager:
     ) -> bool:
         """Returns True when XTerm is active and Cthulhu lacks matching AT-SPI context."""
 
-        if pendingFocus is not None:
-            msg = "INPUT EVENT MANAGER: XTerm matcher false; pending focus exists."
-            debug.print_message(debug.LEVEL_INFO, msg, True)
-            return False
         match = self._active_x11_window_xterm_match()
         tokens = ["INPUT EVENT MANAGER: XTerm matcher returned", match]
         debug.print_tokens(debug.LEVEL_INFO, tokens, True)
         if match is True:
             return True
+        if pendingFocus is not None:
+            msg = "INPUT EVENT MANAGER: XTerm matcher false; pending focus exists."
+            debug.print_message(debug.LEVEL_INFO, msg, True)
+            return False
         if match is None and self._scriptWithSuspendedGrabsForXterm is not None:
             msg = (
                 "INPUT EVENT MANAGER: Keeping XTerm key-grab suspension; "