tools: fix eslint isRequired

Currently the call can lead to a TypeError.

This fixes it by first checking that there are arguments to validate.

The error is triggered by writing: require(). Due to my auto completion in my editor the closing bracket is added as soon as I have a open one and this triggers the eslint rule for e.g. crypto-check or inspector-check and there are obviously no arguments yet in that case.

[Error - 12:54:43 PM] ESLint stack trace:
[Error - 12:54:43 PM] TypeError: Cannot read property 'value' of undefined
    at Object.module.exports.isRequired (/home/ruben/repos/node/node/tools/eslint-rules/rules-utils.js:12:39)
    at checkAssertNode (/home/ruben/repos/node/node/tools/eslint-rules/prefer-assert-iferror.js:27:17)
    at CallExpression (/home/ruben/repos/node/node/tools/eslint-rules/prefer-assert-iferror.js:33:35)
    at listeners.(anonymous function).forEach.listener (/home/ruben/repos/node/node/tools/node_modules/eslint/lib/util/safe-emitter.js:47:58)
    at Array.forEach (native)
    at Object.emit (/home/ruben/repos/node/node/tools/node_modules/eslint/lib/util/safe-emitter.js:47:38)
    at NodeEventGenerator.applySelector (/home/ruben/repos/node/node/tools/node_modules/eslint/lib/util/node-event-generator.js:251:26)
    at NodeEventGenerator.applySelectors (/home/ruben/repos/node/node/tools/node_modules/eslint/lib/util/node-event-generator.js:280:22)
    at NodeEventGenerator.enterNode (/home/ruben/repos/node/node/tools/node_modules/eslint/lib/util/node-event-generator.js:294:14)
    at CodePathAnalyzer.enterNode (/home/ruben/repos/node/node/tools/node_modules/eslint/lib/code-path-analysis/code-path-analyzer.js:608:23)
    at Traverser.enter [as _enter] (/home/ruben/repos/node/node/tools/node_modules/eslint/lib/linter.js:998:32)

Checklist

• make -j4 test (UNIX), or vcbuild test (Windows) passes
• tests and/or benchmarks are included
• documentation is changed or added
• commit message follows commit guidelines

Affected core subsystem(s)

tools