Add missing null check for ctx and input keys in the public API

include/secp256k1.h

@@ -247,7 +247,7 @@ SECP256K1_API secp256k1_context* secp256k1_context_clone(
  */
 SECP256K1_API void secp256k1_context_destroy(
     secp256k1_context* ctx
-);
+) SECP256K1_ARG_NONNULL(1);
 
 /** Set a callback function to be called when an illegal argument is passed to
  *  an API call. It will only trigger for violations that are mentioned

include/secp256k1_preallocated.h

@@ -119,7 +119,7 @@ SECP256K1_API secp256k1_context* secp256k1_context_preallocated_clone(
  */
 SECP256K1_API void secp256k1_context_preallocated_destroy(
     secp256k1_context* ctx
-);
+) SECP256K1_ARG_NONNULL(1);
 
 #ifdef __cplusplus
 }