Fix crash when building history changes

* Replace rarely hit asserts with defined nullptr checks when replacing references without a group
* Fix keepassxreboot#7603
* Replace TOTP history comparison with checking the actual TOTP output instead of a compiled string

src/core/Entry.cpp

@@ -1139,7 +1139,7 @@ QString Entry::resolveReferencePlaceholderRecursive(const QString& placeholder,
     // using format from http://keepass.info/help/base/fieldrefs.html at the time of writing
 
     QRegularExpressionMatch match = EntryAttributes::matchReference(placeholder);
-    if (!match.hasMatch()) {
+    if (!match.hasMatch() || !m_group || !m_group->database()) {
         return placeholder;
     }
 
@@ -1149,8 +1149,6 @@ QString Entry::resolveReferencePlaceholderRecursive(const QString& placeholder,
 
     const EntryReferenceType searchInType = Entry::referenceType(searchIn);
 
-    Q_ASSERT(m_group);
-    Q_ASSERT(m_group->database());
     const Entry* refEntry = m_group->database()->rootGroup()->findEntryBySearchTerm(searchText, searchInType);
 
     if (refEntry) {

src/gui/entry/EntryHistoryModel.cpp

@@ -232,7 +232,7 @@ void EntryHistoryModel::calculateHistoryModifications()
             || curr->timeInfo().expiryTime() != compare->timeInfo().expiryTime()) {
             modifiedFields << tr("Expiration");
         }
-        if (curr->totpSettingsString() != compare->totpSettingsString()) {
+        if (curr->totp() != compare->totp()) {
             modifiedFields << tr("TOTP");
         }
         if (*curr->customData() != *compare->customData()) {