Change ESLint ecmaVersion to 2019, remove unused catch binding.

.eslintrc.json

@@ -1,6 +1,6 @@
 {
   "parserOptions": {
-    "ecmaVersion": 2018
+    "ecmaVersion": 2019
   },
   "env": {
     "node": true,

lib/markdownlint.js

@@ -345,8 +345,7 @@ function getEnabledRulesPerLineNumber(
           ...config,
           ...json
         };
-      // eslint-disable-next-line unicorn/prefer-optional-catch-binding
-      } catch (error) {
+      } catch {
         // Ignore parse errors for inline configuration
       }
     }