util: remove unreachable code in formatNumber

Remove unreachable decimalIndex === -1 defensive branch.

Co-authored-by: Ruben Bridgewater <[email protected]>

Author: Han5991

lib/internal/util/inspect.js

@@ -1698,20 +1698,7 @@ function formatNumber(fn, number, numericSeparator) {
     return fn(numberString, 'number');
   }
 
-	// ---------------------------------------------------------------------------
-	// From this point on, only *non-integer* numbers will reach the code below.
-	// Values where `integer === number` (plain integers, exponential notation,
-	// Infinity, etc.) have already been returned in the previous branch.
-	// For IEEE-754 doubles within the ±2^53 exact-integer range, `String(number)`
-	// never inserts a decimal point, therefore encountering
-	// `decimalIndex === -1` in the next lines should be impossible under
-	// normal circumstances. (kept here as a defensive fallback)
-	// ---------------------------------------------------------------------------
   const decimalIndex = StringPrototypeIndexOf(numberString, '.');
-  if (decimalIndex === -1) {
-    return fn(numberString, 'number');
-  }
-
   const integerPart = StringPrototypeSlice(numberString, 0, decimalIndex);
   const fractionalPart = StringPrototypeSlice(numberString, decimalIndex + 1);