nil check in call utils

Author: ckoegel

spec/call_utils.rb

@@ -41,13 +41,13 @@ def get_manteca_test_status(test_id)
 def cleanup_calls(calls, calls_api)
   attempts = 0
 
-  while (calls.length > 0 && attempts < 10)
+  while (calls&.length > 0 && attempts < 10)
     calls.delete_if { |call_id| call_ended(call_id, calls_api) }
     sleep(SLEEP_TIME_S)
     attempts += 1
   end
 
-  if (calls.length > 0)
+  if (calls&.length > 0)
     error_message = 'Failed to terminate all calls' + calls.to_s
     raise StandardError.new error_message
   end