tslint: no-unused-variable is deprecated.
Since TypeScript 2.9.  We are already using noUnusedLocals in
tsconfig.json.
"no-require-imports": true,
"no-string-throw": true,
"no-unused-expression": true,
- "no-unused-variable": true,
"no-var-keyword": true,
"object-literal-shorthand": true,
"only-arrow-functions": [
