Call - Calling card is not working after enter destination number

Steps:

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1. Register your sip device
2. Dial access number/calling card number
3. Enter card number & pin
4. Dial destination number and observe FS log

Expected result:

================

1. Call should be connected successfully to destination

Actual result:

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1. Call is hangup and FS log showing below error 

FS Log:

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2020-07-03 05:21:09.608449 [ERR] mod_lua.cpp:202 ...switch/scripts/astpp/lib/astpp.callingcard.functions.lua:569: attempt to compare number with nil020-07-03 05:21:09.608449 [ERR] mod_lua.cpp:202 ...switch/scripts/astpp/lib/astpp.callingcard.functions.lua:569: attempt to compare number with nilstack traceback: ...switch/scripts/astpp/lib/astpp.callingcard.functions.lua:569: in function 'process_destination' /usr/share/freeswitch/scripts/astpp-callingcards.lua:103: in main chunk