Bug 422561

SUMMARY
My price updating dialog crashes each time I try to update any currency by hand. It's been like this since I migrated from GnuCash, except I didn't debug it until now.

I initially pinpointed it to the index out of range exception caused by the KEquityPriceUpdateDlg::addInvestment() attempting to split the ID by ' ' without double-checking for trailing spaces.

Adding that check, however, doesn't fix the underlying issue and only prevents the crash from happening. 
Tracing the issue upstream the stack trace I was able to find that:

1) KEquityPriceUpdateDlgPrivate::addPricePair() is not checking whether any of the first or second price symbols in MyMoneySecurityPair object are empty
2) KEquityPriceUpdateDlgPrivate::init() can be initiated with an empty securityId (e.g. when but this is very hacky and not clear it is even supported until the "file->security(pair.first).isCurrency() && (securityId.isEmpty()" expression
3) That expression only checks whether the first item of the pair is a currency and so it continues to run even if the second item of the pair is empty. 
4) The actual underlying cause is my .kmm file somehow got the following added:

  <PRICEPAIR from="PLN" to="">
   <PRICE source="Transaction" date="2013-11-12" price="1/1"/>
   <PRICE source="Transaction" date="2014-02-03" price="1/1"/>
   <PRICE source="Transaction" date="2019-06-28" price="1/1"/>
   <PRICE source="Transaction" date="2019-10-04" price="1/1"/>
   <PRICE source="KMyMoney Currency" date="2020-03-20" price="1/1"/>
  </PRICEPAIR>

The first 5 prices were most likely imported as such from GnuCash. The latter, however, was clearly added by KMyMoney Currency, so this still can be further traced back to some dodgy behavior somewhere else in the app.
STEPS TO REPRODUCE
1. Add a following PRICEPAIR xml element to your statement file
2. Open the Tools->Update Stock and Currency prices
3. Update any currency, close the dialog

OBSERVED RESULT
The app crashes


EXPECTED RESULT
1) The MyMoneySecurityPair type should not allow empty values or KEquityPriceUpdateDlgPrivate::addPricePair() should assert() the pair.first and pair.second are non-empty
2) There shouldn't be any attempt made to add crippled PRICEPAIRs saved at all. 
3) The app shouldn't crash when closing the dialog