Remove NULL checks which are no longer needed

Signed-off-by: Stefan Weil <sw@weilnetz.de>
diff --git a/lib/coding.c b/lib/coding.c
index 1c766d1..e76114d 100644
--- a/lib/coding.c
+++ b/lib/coding.c
@@ -265,9 +265,6 @@
   int len_len;
   int max_len;
 
-  if (der == NULL)
-    return ASN1_VALUE_NOT_VALID;
-
   max_len = *der_len;
 
   asn1_length_der (str_len, (max_len > 0) ? der : NULL, &len_len);
@@ -959,9 +956,6 @@
   unsigned char *out = NULL;
   int err;
 
-  if (der == NULL)
-    return ASN1_VALUE_NOT_VALID;
-
   counter = 0;
 
   if (type_field (node->type) != ASN1_ETYPE_SET_OF)