Adapt chooseFiles() for PyQt6 type hints

The type of the two list arguments of chooseFiles() have changed from
`Iterable[str]` to `Iterable[Optional[str]]`.

I'm not sure it makes much sense to have individual list elements as
None. That seems like a pretty unlikely case. So we could just put an
ignore comment somewhere. I've added another copy of the lists, with
longer names, to strip any hypothetical Nones out. This allows us to be
backwards compatible with the old type hints (and the current Qt5 ones),
since that doesn't have the Optional part in the signature.

ref: qutebrowser#7990

Author: toofar

qutebrowser/browser/webengine/webview.py

@@ -5,7 +5,7 @@
 """The main browser widget for QtWebEngine."""
 
 import mimetypes
-from typing import List, Iterable
+from typing import List, Iterable, Optional
 
 from qutebrowser.qt import machinery
 from qutebrowser.qt.core import pyqtSignal, pyqtSlot, QUrl
@@ -316,29 +316,37 @@ def acceptNavigationRequest(self,
     def chooseFiles(
         self,
         mode: QWebEnginePage.FileSelectionMode,
-        old_files: Iterable[str],
-        accepted_mimetypes: Iterable[str],
+        old_files: Iterable[Optional[str]],
+        accepted_mimetypes: Iterable[Optional[str]],
     ) -> List[str]:
         """Override chooseFiles to (optionally) invoke custom file uploader."""
-        extra_suffixes = extra_suffixes_workaround(accepted_mimetypes)
+        accepted_mimetypes_filtered = [m for m in accepted_mimetypes if m is not None]
+        old_files_filtered = [f for f in old_files if f is not None]
+        extra_suffixes = extra_suffixes_workaround(accepted_mimetypes_filtered)
         if extra_suffixes:
             log.webview.debug(
                 "adding extra suffixes to filepicker: "
-                f"before={accepted_mimetypes} "
+                f"before={accepted_mimetypes_filtered} "
                 f"added={extra_suffixes}",
             )
-            accepted_mimetypes = list(accepted_mimetypes) + list(extra_suffixes)
+            accepted_mimetypes_filtered = list(
+                accepted_mimetypes_filtered
+            ) + list(extra_suffixes)
 
         handler = config.val.fileselect.handler
         if handler == "default":
-            return super().chooseFiles(mode, old_files, accepted_mimetypes)
+            return super().chooseFiles(
+                mode, old_files_filtered, accepted_mimetypes_filtered,
+            )
         assert handler == "external", handler
         try:
             qb_mode = _QB_FILESELECTION_MODES[mode]
         except KeyError:
             log.webview.warning(
                 f"Got file selection mode {mode}, but we don't support that!"
             )
-            return super().chooseFiles(mode, old_files, accepted_mimetypes)
+            return super().chooseFiles(
+                mode, old_files_filtered, accepted_mimetypes_filtered,
+            )
 
         return shared.choose_file(qb_mode=qb_mode)