Repository: microsoft/terminal (language: cpp)

Issue:
'unfocusedAppearance' option with any value including empty dictionary causes Windows Terminal to crash all instances when closing just one
### Windows Terminal version

1.20.11781

### Windows build number

10.0.22631.2861

### Other Software

_No response_

### Steps to reproduce

So after quite a bit of troubleshooting (including re-installing my entire Windows 11 OS), I've narrowed down the bug and can consistently replicate it.


1. Add the `unfocusedAppearance` option in the `defaults` section of your Windows Terminal config, e.g.

```
   "profiles": 
    {
        "defaults": 
        {
            "unfocusedAppearance": 
            {
            }
        },
        ...
    },
```

2. OR alternative use this full config (minimal example):

```md
{
    "$help": "https://aka.ms/terminal-documentation",
    "$schema": "https://aka.ms/terminal-profiles-schema",
    "actions": 
    [
        {
            "command": 
            {
                "action": "copy",
                "singleLine": false
            },
            "keys": "ctrl+c"
        },
        {
            "command": "paste",
            "keys": "ctrl+v"
        },
        {
            "command": "find",
            "keys": "ctrl+shift+f"
        },
        {
            "command": 
            {
                "action": "splitPane",
                "split": "auto",
                "splitMode": "duplicate"
            },
            "keys": "alt+shift+d"
        }
    ],
    "copyFormatting": "none",
    "copyOnSelect": false,
    "defaultProfile": "{61c54bbd-c2c6-5271-96e7-009a87ff44bf}",
    "newTabMenu": 
    [
        {
            "type": "remainingProfiles"
        }
    ],
    "profiles": 
    {
        "defaults": 
        {
            "opacity": 90,
            "unfocusedAppearance": 
            {
            }
        },
        "list": 
        [
            {
                "guid": "{61c54bbd-c2c6-5271-96e7-009a87ff44bf}",
                "hidden": false,
                "name": "Windows PowerShell"
            },
            {
                "guid": "{0caa0dad-35be-5f56-a8ff-afceeeaa6101}",
                "hidden": false,
                "name": "Command Prompt"
            }
        ]
    },
    "schemes": 
    [
        {
            "background": "#0C0C0C",
            "black": "#0C0C0C",
            "blue": "#0037DA",
            "brightBlack": "#767676",
            "brightBlue": "#3B78FF",
            "brightCyan": "#61D6D6",
            "brightGreen": "#16C60C",
            "brightPurple": "#B4009E",
            "brightRed": "#E74856",
            "brightWhite": "#F2F2F2",
            "brightYellow": "#F9F1A5",
            "cursorColor": "#FFFFFF",
            "cyan": "#3A96DD",
            "foreground": "#CCCCCC",
            "green": "#13A10E",
            "name": "Campbell",
            "purple": "#881798",
            "red": "#C50F1F",
            "selectionBackground": "#FFFFFF",
            "white": "#CCCCCC",
            "yellow": "#C19C00"
        },
        {
            "background": "#012456",
            "black": "#0C0C0C",
            "blue": "#0037DA",
            "brightBlack": "#767676",
            "brightBlue": "#3B78FF",
            "brightCyan": "#61D6D6",
            "brightGreen": "#16C60C",
            "brightPurple": "#B4009E",
            "brightRed": "#E74856",
            "brightWhite": "#F2F2F2",
            "brightYellow": "#F9F1A5",
            "cursorColor": "#FFFFFF",
            "cyan": "#3A96DD",
            "foreground": "#CCCCCC",
            "green": "#13A10E",
            "name": "Campbell Powershell",
            "purple": "#881798",
            "red": "#C50F1F",
            "selectionBackground": "#FFFFFF",
            "white": "#CCCCCC",
            "yellow": "#C19C00"
        },
        {
            "background": "#282C34",
            "black": "#282C34",
            "blue": "#61AFEF",
            "brightBlack": "#5A6374",
            "brightBlue": "#61AFEF",
            "brightCyan": "#56B6C2",
            "brightGreen": "#98C379",
            "brightPurple": "#C678DD",
            "brightRed": "#E06C75",
            "brightWhite": "#DCDFE4",
            "brightYellow": "#E5C07B",
            "cursorColor": "#FFFFFF",
            "cyan": "#56B6C2",
            "foreground": "#DCDFE4",
            "green": "#98C379",
            "name": "One Half Dark",
            "purple": "#C678DD",
            "red": "#E06C75",
            "selectionBackground": "#FFFFFF",
            "white": "#DCDFE4",
            "yellow": "#E5C07B"
        },
        {
            "background": "#FAFAFA",
            "black": "#383A42",
            "blue": "#0184BC",
            "brightBlack": "#4F525D",
            "brightBlue": "#61AFEF",
            "brightCyan": "#56B5C1",
            "brightGreen": "#98C379",
            "brightPurple": "#C577DD",
            "brightRed": "#DF6C75",
            "brightWhite": "#FFFFFF",
            "brightYellow": "#E4C07A",
            "cursorColor": "#4F525D",
            "cyan": "#0997B3",
            "foreground": "#383A42",
            "green": "#50A14F",
            "name": "One Half Light",
            "purple": "#A626A4",
            "red": "#E45649",
            "selectionBackground": "#4F525D",
            "white": "#FAFAFA",
            "yellow": "#C18301"
        },
        {
            "background": "#002B36",
            "black": "#002B36",
            "blue": "#268BD2",
            "brightBlack": "#073642",
            "brightBlue": "#839496",
            "brightCyan": "#93A1A1",
            "brightGreen": "#586E75",
            "brightPurple": "#6C71C4",
            "brightRed": "#CB4B16",
            "brightWhite": "#FDF6E3",
            "brightYellow": "#657B83",
            "cursorColor": "#FFFFFF",
            "cyan": "#2AA198",
            "foreground": "#839496",
            "green": "#859900",
            "name": "Solarized Dark",
            "purple": "#D33682",
            "red": "#DC322F",
            "selectionBackground": "#FFFFFF",
            "white": "#EEE8D5",
            "yellow": "#B58900"
        },
        {
            "background": "#FDF6E3",
            "black": "#002B36",
            "blue": "#268BD2",
            "brightBlack": "#073642",
            "brightBlue": "#839496",
            "brightCyan": "#93A1A1",
            "brightGreen": "#586E75",
            "brightPurple": "#6C71C4",
            "brightRed": "#CB4B16",
            "brightWhite": "#FDF6E3",
            "brightYellow": "#657B83",
            "cursorColor": "#002B36",
            "cyan": "#2AA198",
            "foreground": "#657B83",
            "green": "#859900",
            "name": "Solarized Light",
            "purple": "#D33682",
            "red": "#DC322F",
            "selectionBackground": "#073642",
            "white": "#EEE8D5",
            "yellow": "#B58900"
        },
        {
            "background": "#000000",
            "black": "#000000",
            "blue": "#3465A4",
            "brightBlack": "#555753",
            "brightBlue": "#729FCF",
            "brightCyan": "#34E2E2",
            "brightGreen": "#8AE234",
            "brightPurple": "#AD7FA8",
            "brightRed": "#EF2929",
            "brightWhite": "#EEEEEC",
            "brightYellow": "#FCE94F",
            "cursorColor": "#FFFFFF",
            "cyan": "#06989A",
            "foreground": "#D3D7CF",
            "green": "#4E9A06",
            "name": "Tango Dark",
            "purple": "#75507B",
            "red": "#CC0000",
            "selectionBackground": "#FFFFFF",
            "white": "#D3D7CF",
            "yellow": "#C4A000"
        },
        {
            "background": "#FFFFFF",
            "black": "#000000",
            "blue": "#3465A4",
            "brightBlack": "#555753",
            "brightBlue": "#729FCF",
            "brightCyan": "#34E2E2",
            "brightGreen": "#8AE234",
            "brightPurple": "#AD7FA8",
            "brightRed": "#EF2929",
            "brightWhite": "#EEEEEC",
            "brightYellow": "#FCE94F",
            "cursorColor": "#000000",
            "cyan": "#06989A",
            "foreground": "#555753",
            "green": "#4E9A06",
            "name": "Tango Light",
            "purple": "#75507B",
            "red": "#CC0000",
            "selectionBackground": "#555753",
            "white": "#D3D7CF",
            "yellow": "#C4A000"
        },
        {
            "background": "#000000",
            "black": "#000000",
            "blue": "#000080",
            "brightBlack": "#808080",
            "brightBlue": "#0000FF",
            "brightCyan": "#00FFFF",
            "brightGreen": "#00FF00",
            "brightPurple": "#FF00FF",
            "brightRed": "#FF0000",
            "brightWhite": "#FFFFFF",
            "brightYellow": "#FFFF00",
            "cursorColor": "#FFFFFF",
            "cyan": "#008080",
            "foreground": "#C0C0C0",
            "green": "#008000",
            "name": "Vintage",
            "purple": "#800080",
            "red": "#800000",
            "selectionBackground": "#FFFFFF",
            "white": "#C0C0C0",
            "yellow": "#808000"
        }
    ],
    "themes": []
}
```

3. Now launch two instances of Windows Terminal.
4. Using your mouse, press the 'x' button on the top-right of the first instance.
5. The first instance will freeze a bit, crash, and cause both instances to shut.
6. If you view Event Viewer logs, under Application logs, you will see that the application has indeed crashed with an ERROR.

Other things to know:
- Removing the `unfocusedAppearance` option fixes the issue (but you lose that feature).
- The `unfocusedAppearance` use to work for me on older builds (I don't know which ones but I use to use this feature a lot).
- Adding any options in the `unfocusedAppearance` still causes the crash.
- Shutting any of the Windows Terminal using 'CTRL+W' shortcut avoids this crashing behaviour.

### Expected Behavior

When I shut a single instance of Windows Terminal, it should only shut that instance and not shut all other instances. This likely happens because the parent process crashes, killing all spawned windows terminal children.

### Actual Behavior

Pressing the 'x' button causes all windows terminal instances to shut.


Discussion / hints:

Fix patch:
diff --git a/src/cascadia/TerminalControl/TermControl.cpp b/src/cascadia/TerminalControl/TermControl.cpp
index 045762a3ac0..8f8f9f0df66 100644
--- a/src/cascadia/TerminalControl/TermControl.cpp
+++ b/src/cascadia/TerminalControl/TermControl.cpp
@@ -717,11 +717,14 @@ namespace winrt::Microsoft::Terminal::Control::implementation
         // terminal.
         co_await wil::resume_foreground(Dispatcher());
 
-        _core.UpdateSettings(settings, unfocusedAppearance);
+        if (auto strongThis{ weakThis.get() })
+        {
+            _core.UpdateSettings(settings, unfocusedAppearance);
 
-        _UpdateSettingsFromUIThread();
+            _UpdateSettingsFromUIThread();
 
-        _UpdateAppearanceFromUIThread(_focused ? _core.FocusedAppearance() : _core.UnfocusedAppearance());
+            _UpdateAppearanceFromUIThread(_focused ? _core.FocusedAppearance() : _core.UnfocusedAppearance());
+        }
     }
 
     // Method Description:
@@ -730,10 +733,15 @@ namespace winrt::Microsoft::Terminal::Control::implementation
     // - newAppearance: the new appearance to set
     winrt::fire_and_forget TermControl::UpdateAppearance(IControlAppearance newAppearance)
     {
+        auto weakThis{ get_weak() };
+
         // Dispatch a call to the UI thread
         co_await wil::resume_foreground(Dispatcher());
 
-        _UpdateAppearanceFromUIThread(newAppearance);
+        if (auto strongThis{ weakThis.get() })
+        {
+            _UpdateAppearanceFromUIThread(newAppearance);
+        }
     }
 
     // Method Description:


Test patch: