ESLint/TypeScript: enforce no-implicit-any-catch

TypeScript try/catch and RxJs catchError are not type-safe.

https://typescript-eslint.io/rules/no-implicit-any-catch/
https://devblogs.microsoft.com/typescript/announcing-typescript-4-0/#unknown-on-catch
https://github.com/cartant/eslint-plugin-rxjs/blob/main/docs/rules/no-implicit-any-catch.md

.eslintrc.json

@@ -239,7 +239,6 @@
           "method"
         ],
 
-        "rxjs/no-implicit-any-catch": "off",  // todo: investigate how best to solve these
         "rxjs/no-nested-subscribe": "off"     // todo: go over _all_ cases
       }
     },

tsconfig.json

@@ -40,7 +40,8 @@
       "node",
       "jasmine"
     ],
-    "useDefineForClassFields": false
+    "useDefineForClassFields": false,
+    "useUnknownInCatchVariables": true
   },
   "angularCompilerOptions": {
     "fullTemplateTypeCheck": true,