gts check fails silently on NodeJS 8

[dotdoom]

Since the exception is not printed here:

gts/src/cli.ts

Lines 130 to 132 in 156cb02

	} catch (e) {
	return false;
	}

npm run check fails (exit code 1) without any error output.

Perhaps this needs a bold, noticeable hint in README that NodeJS 8 is unsupported?

[jabolina]

Seems like is also failing for NodeJS 9.9.0