Problem

When using webpack filename templates with length-limited content hashes (e.g., [contenthash:12]), the hash truncation was performed using simple string slicing (hash.slice(0, length)). This could result in truncated hashes that contain only numeric characters, which can cause issues when RealContentHashPlugin try to replace the content hash with real content hash. #14058

Root Cause

The hashLength function in TemplatedPathPlugin.js used simple string slicing:

// Before: Could produce numeric-only hashes
result = length ? hash.slice(0, length) : hash;

When a hash like "123456789101acbdefgh" was truncated to 12 characters, it could produce "123456789101" - a purely numeric string. This creates problems for RealContentHashPlugin which expects to find and replace these hash patterns.

Fix

Use existing nonNumericOnlyHash utility function that webpack already uses internally: