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

lib/parse-configuration.mjs

@@ -4,7 +4,7 @@
  * Result of a call to parseConfiguration.
  *
  * @typedef {Object} ParseConfigurationResult
- * @property {Object | null} config Configuration object if successful.
+ * @property {import("markdownlint").Configuration | null} config Configuration object if successful.
  * @property {string | null} message Error message if an error occurred.
  */
 
@@ -13,7 +13,7 @@
  *
  * @param {string} name Name of the configuration file.
  * @param {string} content Configuration content.
- * @param {import("./markdownlint.mjs").ConfigurationParser[]} [parsers] Parsing function(s).
+ * @param {import("markdownlint").ConfigurationParser[]} [parsers] Parsing function(s).
  * @returns {ParseConfigurationResult} Parse configuration result.
  */
 export default function parseConfiguration(name, content, parsers) {
@@ -28,8 +28,9 @@ export default function parseConfiguration(name, content, parsers) {
       config = (result && (typeof result === "object") && !Array.isArray(result)) ? result : {};
       // Succeeded
       return false;
-    } catch(error) {
-      errors.push(`Parser ${index++}: ${error.message}`);
+      // eslint-disable-next-line jsdoc/reject-any-type
+    } catch(/** @type {any} */ error) {
+      errors.push(`Parser ${index++}: ${error?.message}`);
     }
     // Failed, try the next parser
     return true;