cjose_base64url_decode returns inconsistent output

[divyaraghavendran]

I am using the cjose library to create a JWT which will be used while exchanging information with a third-party client.

I found that sometimes, the library returns the below error:
JWT library error: invalid argument in file:jwe.c and func:_cjose_jwe_set_cek_aes_cbc
and line:448
This happens on my call to cjose_jwe_encrypt(jwk, header, (uint8_t*)compact_jws, comp_jws_len, &err);

I traced down the problem, and what I found was the value returned from cjose_base64url_decode() sometimes changes i.e. the output string value returned changes randomly, even though the provided input and inlen remains the same.
I cannot find any reason for this return value to vary even though the input remains constant.

Would it be possible to provide a fix for this or a workaround?