Fix Staticfiles 404.html in HTML mode

starlette/staticfiles.py

@@ -111,20 +111,6 @@ async def get_response(self, path: str, scope: Scope) -> Response:
             full_path, stat_result = await anyio.to_thread.run_sync(
                 self.lookup_path, path
             )
-        except (FileNotFoundError, NotADirectoryError):
-            if self.html:
-                # Check for '404.html' if we're in HTML mode.
-                full_path, stat_result = await anyio.to_thread.run_sync(
-                    self.lookup_path, "404.html"
-                )
-                if stat_result and stat.S_ISREG(stat_result.st_mode):
-                    return FileResponse(
-                        full_path,
-                        stat_result=stat_result,
-                        method=scope["method"],
-                        status_code=404,
-                    )
-            raise HTTPException(status_code=404)
         except PermissionError:
             raise HTTPException(status_code=401)
         except OSError:
@@ -149,6 +135,18 @@ async def get_response(self, path: str, scope: Scope) -> Response:
                     return RedirectResponse(url=url)
                 return self.file_response(full_path, stat_result, scope)
 
+        if self.html:
+            # Check for '404.html' if we're in HTML mode.
+            full_path, stat_result = await anyio.to_thread.run_sync(
+                self.lookup_path, "404.html"
+            )
+            if stat_result and stat.S_ISREG(stat_result.st_mode):
+                return FileResponse(
+                    full_path,
+                    stat_result=stat_result,
+                    method=scope["method"],
+                    status_code=404,
+                )
         raise HTTPException(status_code=404)
 
     def lookup_path(
@@ -161,7 +159,10 @@ def lookup_path(
                 # Don't allow misbehaving clients to break out of the static files
                 # directory.
                 continue
-            return full_path, os.stat(full_path)
+            try:
+                return full_path, os.stat(full_path)
+            except (FileNotFoundError, NotADirectoryError):
+                continue
         return "", None
 
     def file_response(