Type catch arguments as `any` rather than `unknown`

Disable a change/feature added in TypeScript 4.4 so that our existing
code typechecks. In most cases the handler is just making the pretty safe
assumption that the thrown error is a subclass of `Error`.

src/tsconfig.json

@@ -9,7 +9,10 @@
     "noEmit": true,
     "strict": true,
     "noImplicitAny": false,
-    "target": "ES2020"
+    "target": "ES2020",
+
+    // Let argument to catch statement be `any` rather than `unknown`.
+    "useUnknownInCatchVariables": false
   },
   "include": ["**/*.js"],
   "exclude": [