improving examples #2: fixing my mistakes; changing comments

Author: Cheapshot003

examples/ecdh.c

@@ -50,8 +50,8 @@ int main(void) {
         printf("Failed to generate randomness\n");
         return 1;
     }
-    if (secp256k1_ec_seckey_verify(ctx, seckey1) && secp256k1_ec_seckey_verify(ctx, seckey2)) {
-        break;
+    if (!secp256k1_ec_seckey_verify(ctx, seckey1) || !secp256k1_ec_seckey_verify(ctx, seckey2)) {
+        return 1;
     }
 
     /* Public key creation using a valid context with a verified secret key should never fail */

examples/ecdsa.c

@@ -51,14 +51,14 @@ int main(void) {
     /*** Key Generation ***/
 
     /* If the secret key is zero or out of range (bigger than secp256k1's
-     * order), we try to sample a new key. Note that the probability of this
-     * happening is negligible. */
+     * order), we return 1. Note that the probability of this
+     * happening is negligible, though it could indicate a faulty RNG */
     if (!fill_random(seckey, sizeof(seckey))) {
         printf("Failed to generate randomness\n");
         return 1;
     }
-    if (secp256k1_ec_seckey_verify(ctx, seckey)) {
-        break;
+    if (!secp256k1_ec_seckey_verify(ctx, seckey)) {
+        return 1;
     }
 
     /* Public key creation using a valid context with a verified secret key should never fail */

examples/ellswift.c

@@ -49,14 +49,15 @@ int main(void) {
     /*** Generate secret keys ***/
 
     /* If the secret key is zero or out of range (bigger than secp256k1's
-     * order), we try to sample a new key. Note that the probability of this
-     * happening is negligible. */
+     * order), we return 1. Note that the probability of this
+     * happening is negligible, though it could indicate a faulty RNG */
     if (!fill_random(seckey1, sizeof(seckey1)) || !fill_random(seckey2, sizeof(seckey2))) {
         printf("Failed to generate randomness\n");
         return 1;
     }
-    if (secp256k1_ec_seckey_verify(ctx, seckey1) && secp256k1_ec_seckey_verify(ctx, seckey2)) {
-        break;
+    if (!secp256k1_ec_seckey_verify(ctx, seckey1) || !secp256k1_ec_seckey_verify(ctx, seckey2)) {
+        printf("Generated secret key is invalid. This could indicate an issue with the random number generator.\n")
+        return 1;
     }
 
     /* Generate ElligatorSwift public keys. This should never fail with valid context and