Transactions above 20k now show correct error message

[kokrui]

Closes #232

[lordidiot]

LGTM! Appreciate the addition of tests and more verbose naming.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (b27bdb6) 82.83% compared to head (1ae1a16) 83.02%.

Additional details and impacted files

@@             Coverage Diff              @@
##             master     #233      +/-   ##
============================================
+ Coverage     82.83%   83.02%   +0.18%     
- Complexity      773      777       +4     
============================================
  Files           100      100              
  Lines          2377     2380       +3     
  Branches        267      267              
============================================
+ Hits           1969     1976       +7     
+ Misses          338      336       -2     
+ Partials         70       68       -2     

Files	Coverage Δ
...in/java/seedu/address/logic/parser/ParserUtil.java	97.26% <100.00%> (+0.07%)	⬆️
.../main/java/seedu/address/model/person/Balance.java	100.00% <100.00%> (+16.66%)	⬆️
.../java/seedu/address/storage/JsonAdaptedPerson.java	100.00% <100.00%> (ø)

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