fix: Allow no tickets amount calculation with discount

[iamareebjamal]

No description provided.

[codecov]

Codecov Report

Merging #7034 into development will not change coverage.
The diff coverage is 100.00%.

@@             Coverage Diff              @@
##           development    #7034   +/-   ##
============================================
  Coverage        60.56%   60.56%           
============================================
  Files              259      259           
  Lines            12874    12874           
============================================
  Hits              7797     7797           
  Misses            5077     5077           

Impacted Files	Coverage Δ
app/api/helpers/order.py	65.28% <100.00%> (ø)

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