Impossible to convert from entropy to mnemonic in example.c

[AlexInsa]

With the file example.c, it is not possible to use the functionality "-e entropy_file", because the return of the function entropy_to_mnemonic is not well treated.

Indeed, according to the documentation of the function entropy_to_mnemonic in mnemonics.h, and according to this associated source code in mnemonics.c the function returns the

length of mnemonic phrase in characters or negative error code in case of failure

However, in the example.c file, in the function convert_entropy_to_mnemonics, the variable return_code is compared to 0 :

/* Converting entropy to a mnemonic phrase using the default dictionary. */
    return_code = entropy_to_mnemonic(NULL, entropy, entropy_len, &mnemonic);

    if (return_code != 0) {
        printf("Error: Could not convert entropy.\n");
        return;
    }

This means that, if the entropy_to_mnemonic function returns the correct output (the length of the mnemonic phrase), then the program stops and prints that an error occurred.

One of the possible patch would be to change the error return check :

if (return_code != 0) {

by

if (return_code <= 0) {

in example.c