Further improve type annotations, reduce mypy whitelist (#10770)

Co-authored-by: Adam Turner <9087854+aa-turner@users.noreply.github.com>

2 files changed, 13 insertions, 11 deletions

diff --git a/sphinx/builders/latex/theming.py b/sphinx/builders/latex/theming.py
index 6bcdc7f9d..5f8300084 100644
--- a/sphinx/builders/latex/theming.py
+++ b/sphinx/builders/latex/theming.py
@@ -2,7 +2,7 @@
 
 import configparser
 from os import path
-from typing import Dict
+from typing import Dict, Optional
 
 from sphinx.application import Sphinx
 from sphinx.config import Config
@@ -113,14 +113,12 @@ class ThemeFactory:
         if name in self.themes:
             theme = self.themes[name]
         else:
-            theme = self.find_user_theme(name)
-            if not theme:
-                theme = Theme(name)
+            theme = self.find_user_theme(name) or Theme(name)
 
         theme.update(self.config)
         return theme
 
-    def find_user_theme(self, name: str) -> Theme:
+    def find_user_theme(self, name: str) -> Optional[Theme]:
         """Find a theme named as *name* from latex_theme_path."""
         for theme_path in self.theme_paths:
             config_path = path.join(theme_path, name, 'theme.conf')
diff --git a/sphinx/builders/latex/transforms.py b/sphinx/builders/latex/transforms.py
index 5e478f5c4..e996250f7 100644
--- a/sphinx/builders/latex/transforms.py
+++ b/sphinx/builders/latex/transforms.py
@@ -1,6 +1,6 @@
 """Transforms for LaTeX builder."""
 
-from typing import Any, Dict, List, Set, Tuple, cast
+from typing import Any, Dict, List, Optional, Set, Tuple, cast
 
 from docutils import nodes
 from docutils.nodes import Element, Node
@@ -94,13 +94,17 @@ class ShowUrlsTransform(SphinxPostTransform):
     def get_docname_for_node(self, node: Node) -> str:
         while node:
             if isinstance(node, nodes.document):
-                return self.env.path2doc(node['source'])
+                return self.env.path2doc(node['source']) or ''
             elif isinstance(node, addnodes.start_of_file):
                 return node['docname']
             else:
                 node = node.parent
 
-        return None  # never reached here. only for type hinting
+        try:
+            source = node['source']  # type: ignore[index]
+        except TypeError:
+            raise ValueError('Failed to get a docname!') from None
+        raise ValueError(f'Failed to get a docname for source {source!r}!')
 
     def create_footnote(self, uri: str, docname: str) -> Tuple[nodes.footnote, nodes.footnote_reference]:  # NOQA
         reference = nodes.reference('', nodes.Text(uri), refuri=uri, nolinkurl=True)
@@ -355,7 +359,7 @@ class LaTeXFootnoteVisitor(nodes.NodeVisitor):
         self.footnotes: List[nodes.footnote] = footnotes
         self.pendings: List[nodes.footnote] = []
         self.table_footnotes: List[nodes.footnote] = []
-        self.restricted: Element = None
+        self.restricted: Optional[Element] = None
         super().__init__(document)
 
     def unknown_visit(self, node: Node) -> None:
@@ -433,7 +437,7 @@ class LaTeXFootnoteVisitor(nodes.NodeVisitor):
         number = node.astext().strip()
         docname = node['docname']
         if (docname, number) in self.appeared:
-            footnote = self.appeared.get((docname, number))
+            footnote = self.appeared[(docname, number)]
             footnote["referred"] = True
 
             mark = footnotemark('', number, refid=node['refid'])
@@ -458,7 +462,7 @@ class LaTeXFootnoteVisitor(nodes.NodeVisitor):
             if docname == footnote['docname'] and footnote['ids'][0] == node['refid']:
                 return footnote
 
-        return None
+        raise ValueError('No footnote not found for given reference node %r' % node)
 
 
 class BibliographyTransform(SphinxPostTransform):