fix: raise ValueError instead of TypeError in issuer_or_subject_length (#30)

Corrected the check when all issuer/subject fields are empty.
Previously raised TypeError (misleading), now raises ValueError.
Fixes #30.

Author: ritesh006

adafruit_atecc/adafruit_atecc_asn1.py

@@ -268,6 +268,8 @@ def issuer_or_subject_length(
         tot_len += 11 + len(org_unit)
     if common:
         tot_len += 11 + len(common)
-    else:
-        raise TypeError("Provided length must be > 0")
-    return tot_len
+
+    if tot_len == 0:
+        raise TypeError("issuer_or_subject_length cannot be zero")
+
+    return tot_len