Errors in writing the output configuration file are ignored

[JoshuaKGoldberg]

🐛 Bug Report

• tslint-to-eslint-config version: 0.1.7
• ESLint version: N/A
• Node version: 8.X

Actual Behavior

npx tslint-to-eslint-config prints out happy console messages but doesn't signal any error when creating an output .eslintrc.js file fails.

Expected Behavior

Logging the error and exiting with a non-zero status code would sure be nice!

There's a line something like await dependencies.writeConfigurationFile(...); where the result value is ignored. If that write method returns a failure result, that should be returned by runCli as a failure result.

Reproduction

mkdir temp
cd temp
npm init --yes
echo "{}" > tslint.json
npx tslint-to-eslint-config

This will fail silently on Node 8.X because of #63. Note that #63 tracks fixing the Node 8 crash; this issue is for correctly logging any failure such as that one. Presumably, this issue will come up again if the writing of the configuration file fails for a permissions issue.