fix: do not throw on a negative number space

[spokodev]

Problem

stringify throws on a negative numeric space, while JSON.stringify treats any value below 1 as no indentation:

JSON.stringify({ a: 1 }, null, -1)  // '{"a":1}'
stringify({ a: 1 }, null, -1)       // RangeError: Invalid count value: -1

It throws for every numeric space that truncates to <= -1 (-1, -5, -Infinity). -0.9 already works because it truncates toward 0, which pins the cause.

The README documents the spacer as behaving "the same as with JSON.stringify()", and ECMA-262 JSON.stringify computes the gap as min(10, ToIntegerOrInfinity(space)) and uses no indentation for any value < 1 — it never throws.

Cause

index.js:

spacer = ' '.repeat(Math.min(space, 10))

space is clamped to a maximum of 10 but not a minimum of 0, so a negative count reaches String.prototype.repeat, which throws for counts <= -1.

Fix

Clamp the lower bound to 0:

spacer = ' '.repeat(Math.max(0, Math.min(space, 10)))

Verification

Added a negative spacer length test asserting equality with JSON.stringify for -1, -1e5, and -Infinity. It throws on main and passes with the fix. Full suite (standard + tap) green.