Fix: extract pwd field more properly

[ahmetsari]

• extract pwd field more properly
• null check for pwd before sending as non-null parameter

[jitsi-jenkins]

Hi, thanks for your contribution!
If you haven't already done so, could you please make sure you sign our CLA (https://jitsi.org/icla for individuals and https://jitsi.org/ccla for corporations)? We would unfortunately be unable to merge your patch unless we have that piece :(.