close Anki after a panic occurs

Once the mutex has been poisoned the app is unusable, and users were
struggling to close it. This also ensures we'll receive the original
error report, instead of the follow-up poison errors that don't tell us
what caused the issue.

https://forums.ankiweb.net/t/error-message-keeps-popping-up/10494

qt/aqt/errors.py

@@ -93,7 +93,14 @@ class ErrorHandler(QObject):
             showWarning(markdown(tr.errors_accessing_db()))
             return
 
-        if self.mw.addonManager.dirty:
+        must_close = False
+        if "PanicException" in error:
+            must_close = True
+            txt = markdown(
+                "**A fatal error occurred, and Anki must close. Please report this message on the forums.**"
+            )
+            error = f"{supportText() + self._addonText(error)}\n{error}"
+        elif self.mw.addonManager.dirty:
             txt = markdown(tr.errors_addons_active_popup())
             error = f"{supportText() + self._addonText(error)}\n{error}"
         else:
@@ -103,6 +110,8 @@ class ErrorHandler(QObject):
         # show dialog
         txt = f"{txt}<div style='white-space: pre-wrap'>{error}</div>"
         showText(txt, type="html", copyBtn=True)
+        if must_close:
+            sys.exit(1)
 
     def _addonText(self, error: str) -> str:
         matches = re.findall(r"addons21/(.*?)/", error)