Configuration for rule "no-underscore-dangle" is invalid

[bouzuya]

🐛 Bug Report

• tslint-to-eslint-config version: 0.4.0
• ESLint version: 6.7.2
• Node version: 12.14.0

Actual Behavior

.eslintrc.js

module.exports = {
    ...
    "no-underscore-dangle": [
            "error",
            "off"
        ]
    ...
};

$ eslint index.ts
Error: .eslintrc.js:
        Configuration for rule "no-underscore-dangle" is invalid:
        Value "off" should be object.

Expected Behavior

module.exports = {
    ...
    "no-underscore-dangle": [
            "off"
        ]
    ...
};

Reproduction

#!/bin/bash
mkdir example
cd example/
node --version # v12.14.0
npm init -y
npm i -D \
  @typescript-eslint/parser@2.12.0 \
  @typescript-eslint/eslint-plugin@2.12.0 \
  eslint@6.7.2 \
  tslint@5.20.1 \
  typescript@3.7.3
cat <<EOS >tslint.json
{
  "rules": {
    "variable-name": [
      true,
      "check-format",
      "allow-leading-underscore"
    ]
  }
}
EOS
$(npm bin)/tsc --init
npx tslint-to-eslint-config@0.4.0

cat .eslintrc.js # generated
# module.exports = {
#     "env": {
#         "browser": true,
#         "es6": true
#     },
#     "parser": "@typescript-eslint/parser",
#     "parserOptions": {
#         "project": "tsconfig.json",
#         "sourceType": "module"
#     },
#     "plugins": [
#         "@typescript-eslint"
#     ],
#     "rules": {
#         "camelcase": "error",
#         "id-blacklist": "error",
#         "id-match": "error",
#         "no-underscore-dangle": [
#             "error",
#             "off"
#         ]
#     }
# };

# dummy source file
cat <<EOS >index.ts
function add(x: number, y: number) {
  return x + y;
}
EOS

$(npm bin)/eslint index.ts
# Error: .eslintrc.js:
#         Configuration for rule "no-underscore-dangle" is invalid:
#         Value "off" should be object.

[bouzuya]

#266