Address new TypeScript warnings in core files, improve type definitions.

test/snapshots/markdownlint-test-scenarios.mjs.md

@@ -60691,6 +60691,48 @@ Generated by [AVA](https://avajs.dev).
           ],
           severity: 'error',
         },
+        {
+          errorContext: null,
+          errorDetail: 'Expected: plus; Actual: dash',
+          errorRange: [
+            13,
+            1,
+          ],
+          fixInfo: {
+            deleteCount: 1,
+            editColumn: 13,
+            insertText: '+',
+          },
+          lineNumber: 66,
+          ruleDescription: 'Unordered list style',
+          ruleInformation: 'https://github.com/DavidAnson/markdownlint/blob/v0.0.0/doc/md004.md',
+          ruleNames: [
+            'MD004',
+            'ul-style',
+          ],
+          severity: 'error',
+        },
+        {
+          errorContext: null,
+          errorDetail: 'Expected: asterisk; Actual: plus',
+          errorRange: [
+            15,
+            1,
+          ],
+          fixInfo: {
+            deleteCount: 1,
+            editColumn: 15,
+            insertText: '*',
+          },
+          lineNumber: 75,
+          ruleDescription: 'Unordered list style',
+          ruleInformation: 'https://github.com/DavidAnson/markdownlint/blob/v0.0.0/doc/md004.md',
+          ruleNames: [
+            'MD004',
+            'ul-style',
+          ],
+          severity: 'error',
+        },
       ],
       fixed: `# sublist-bullet-style␊
       ␊
@@ -60751,6 +60793,23 @@ Generated by [AVA](https://avajs.dev).
                 - item␊
                 - item {MD004}␊
       ␊
+      - item␊
+        * item␊
+          + item␊
+            - item␊
+              * item␊
+                - item␊
+                  + item {MD004}␊
+      ␊
+      - item␊
+        * item␊
+          + item␊
+            - item␊
+              * item␊
+                - item␊
+                  + item␊
+                    * item {MD004}␊
+      ␊
       <!-- markdownlint-configure-file {␊
         "ul-style": {␊
           "style": "sublist"␊

test/sublist-bullet-style.md

@@ -57,6 +57,23 @@
           - item
           + item {MD004}
 
+- item
+  * item
+    + item
+      - item
+        * item
+          - item
+            - item {MD004}
+
+- item
+  * item
+    + item
+      - item
+        * item
+          - item
+            + item
+              + item {MD004}
+
 <!-- markdownlint-configure-file {
   "ul-style": {
     "style": "sublist"