bug: EAN-13 does not validate provided check digit

[productdevbook]

Summary

When a 13-digit EAN-13 code is provided (with check digit), src/encoders/ean.ts does not validate that the check digit is correct. In contrast, src/encoders/upc.ts correctly validates UPC-A check digits.

Details

ean.ts (NO validation):

export function encodeEAN13(text: string) {
  const digits = text.replace(/\D/g, "").split("").map(Number);
  if (digits.length === 12) {
    digits.push(calculateCheckDigit(digits));
  } else if (digits.length !== 13) {
    throw new Error("EAN-13 requires 12 or 13 digits");
  }
  // No check digit validation for 13-digit input!
}

upc.ts (HAS validation):

export function encodeUPCA(text: string) {
  // ...
  } else if (digits.length === 12) {
    const expected = calculateCheckDigit(digits.slice(0, 11));
    if (digits[11] !== expected) {
      throw new InvalidInputError(
        `UPC-A check digit mismatch: expected ${expected}, got ${digits[11]}`
      );
    }
  }
}

The same issue exists in encodeEAN8() — no check digit validation for 8-digit input.

Impact

Invalid EAN-13/EAN-8 codes with wrong check digits are silently accepted and encoded, producing barcodes that will fail at point-of-sale verification.

Fix

Add check digit validation for 13-digit EAN-13 and 8-digit EAN-8 input, matching the pattern used in UPC-A. Also use InvalidInputError instead of plain Error.

[productdevbook]

Fixed in commit a0867b3 / e4631a5 / b4e8107