cid#1607024 silence Overflowed constant

and

cid#1607900 silence Overflowed constant

Change-Id: I18ef4b6885f872697c272b9fedc6a3e92a0df587
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/174492
Tested-by: Jenkins
Reviewed-by: Caolán McNamara <caolan.mcnamara@collabora.com>

cppuhelper/source/servicemanager.cxx

@@ -1466,6 +1466,7 @@ OUString cppuhelper::ServiceManager::readLegacyRdbString(
     }
     OUString val;
     std::vector< char > v(s); // assuming sal_uInt32 fits into vector::size_type
+    assert(s > 0 && "throw above otherwise");
     if (subkey.getValue(OUString(), v.data()) != RegError::NO_ERROR
         || v.back() != '\0'
         || !rtl_convertStringToUString(

cui/source/customize/cfg.cxx

@@ -2983,6 +2983,7 @@ bool SvxIconSelectorDialog::ReplaceGraphicItem(
     for (size_t n = 0; n < nCount; ++n)
     {
         sal_uInt16 nId = m_xTbSymbol->GetItemId( n );
+        assert(nId > 0 && "otherwise totally broken");
 
         if ( m_xTbSymbol->GetItemText( nId ) == aURL )
         {