Fix: ensure "version" always has a valid value in parseOptions

[ZauberNerd]

The rule no-unsupported-features would sometimes fail with a TypeError:

Error while loading rule 'node/no-unsupported-features': Cannot read property 'split' of null TypeError: Error while loading rule 'node/no-unsupported-features': Cannot read property 'split' of null at new Range (.../node_modules/semver/semver.js:780:20) at Function.intersects (.../node_modules/semver/semver.js:1305:8) at Object.freeze.features.Object.freeze.OPTIONS.reduce (.../node_modules/eslint-plugin-node/lib/rules/no-unsupported-features.js:191:44) at Array.reduce (<anonymous>) at parseOptions (.../node_modules/eslint-plugin-node/lib/rules/no-unsupported-features.js:175:41) at Object.create (.../node_modules/eslint-plugin-node/lib/rules/no-unsupported-features.js:281:25) 

This happens, when neither "engines" are set in the "package.json",
nor "version" is set in the rule configuration but the rule still has
configuration options, because version will then be set to
options.version, even if that is undefined.

This commit ensures that version always has a valid value before
trying to construct a semver range from it.

[codecov-io]

Codecov Report

Merging #109 into master will not change coverage.
The diff coverage is 100%.

@@ Coverage Diff @@ ## master #109 +/- ## ======================================= Coverage 98.21% 98.21% ======================================= Files 43 43 Lines 1065 1065 ======================================= Hits 1046 1046 Misses 19 19

Impacted Files	Coverage Δ
lib/rules/no-unsupported-features.js	97.39% <100%> (ø)	⬆️

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[mysticatea]

Oh, thank you for the contribution!

It looks a regression in #99 I had overlooked.
Would you move the change to getDefaultVersion function? The getDefaultVersion function should return a string always, but now it can return null.

[ZauberNerd]

@mysticatea updated, please take another look :)

[ZauberNerd]

Hi @mysticatea just wanted to ask whether you had time already to take another look at this and if there's anything I can help with to get the fix released.

[mysticatea]

I apologize for my delay. LGTM!

[ZauberNerd]

No worries, thank you!