On startup, KMines calls MineFieldItem::adjustItemPositions() three times. That methods uses MineFieldItem:m_cellSize which is undefined at that point, because resizeToFitInRect has not been called, yet. Only the third call to adjustItemPositions makes sense.

first call:
#0  MineFieldItem::adjustItemPositions (this=0x6e12a0) at kmines-15.08.0/minefielditem.cpp:249
#1  0x00000000004250f2 in MineFieldItem::initField (this=0x6e12a0, numRows=9, numCols=9, numMines=10) at kmines-15.08.0/minefielditem.cpp:93
#2  0x000000000042af6e in KMinesScene::startNewGame (this=0x70ca60, rows=9, cols=9, numMines=10) at kmines-15.08.0/scene.cpp:96
#3  0x000000000041ddce in KMinesMainWindow::newGame (this=0x717350) at kmines-15.08.0/mainwindow.cpp:163
#4  0x000000000041d8cf in KMinesMainWindow::KMinesMainWindow (this=0x717350, __in_chrg=<optimized out>, __vtt_parm=<optimized out>)
    at kmines-15.08.0/mainwindow.cpp:116
#5  0x000000000042c78e in main (argc=1, argv=0x7fffffffd508) at kmines-15.08.0/main.cpp:80

second call:
#0  MineFieldItem::adjustItemPositions (this=0x6e12a0) at kmines-15.08.0/minefielditem.cpp:249
#1  0x0000000000425ad2 in MineFieldItem::resizeToFitInRect (this=0x6e12a0, rect=...) at kmines-15.08.0/minefielditem.cpp:242
#2  0x000000000042aabf in KMinesScene::resizeScene (this=0x70ca60, width=128136736, height=79929520) at kmines-15.08.0/scene.cpp:82
#3  0x000000000042afd8 in KMinesScene::startNewGame (this=0x70ca60, rows=9, cols=9, numMines=10) at kmines-15.08.0/scene.cpp:98
#4  0x000000000041ddce in KMinesMainWindow::newGame (this=0x717350) at kmines-15.08.0/mainwindow.cpp:163
#5  0x000000000041d8cf in KMinesMainWindow::KMinesMainWindow (this=0x717350, __in_chrg=<optimized out>, __vtt_parm=<optimized out>)
    at kmines-15.08.0/mainwindow.cpp:116
#6  0x000000000042c78e in main (argc=1, argv=0x7fffffffd508) at kmines-15.08.0/main.cpp:80

third call:
#0  MineFieldItem::adjustItemPositions (this=0x6e12a0) at kmines-15.08.0/minefielditem.cpp:249
#1  0x0000000000425ad2 in MineFieldItem::resizeToFitInRect (this=0x6e12a0, rect=...) at kmines-15.08.0/minefielditem.cpp:242
#2  0x000000000042aabf in KMinesScene::resizeScene (this=0x70ca60, width=845, height=520) at kmines-15.08.0/scene.cpp:82
#3  0x000000000042a2a9 in KMinesView::resizeEvent (this=0x84abf0, ev=0x7fffffffcef0) at kmines-15.08.0/scene.cpp:39
#4  0x00007ffff5275f52 in QWidget::event (this=this@entry=0x84abf0, event=event@entry=0x7fffffffcef0) at kernel/qwidget.cpp:8826
#5  0x00007ffff53506c0 in QFrame::event (this=this@entry=0x84abf0, e=e@entry=0x7fffffffcef0) at widgets/qframe.cpp:540
#6  0x00007ffff53d2d6a in QAbstractScrollArea::viewportEvent (this=this@entry=0x84abf0, e=e@entry=0x7fffffffcef0) at widgets/qabstractscrollarea.cpp:1200
#7  0x00007ffff554f05e in QGraphicsView::viewportEvent (this=0x84abf0, event=0x7fffffffcef0) at graphicsview/qgraphicsview.cpp:2962
#8  0x00007ffff53d3651 in viewportEvent (event=<optimized out>, this=<optimized out>) at widgets/qabstractscrollarea_p.h:102
#9  QAbstractScrollAreaFilter::eventFilter (this=<optimized out>, o=<optimized out>, e=<optimized out>) at widgets/qabstractscrollarea_p.h:118
#10 0x00007ffff49b09ac in QCoreApplicationPrivate::sendThroughObjectEventFilters (this=this@entry=0x63aa60, receiver=receiver@entry=0x860a50, 
    event=event@entry=0x7fffffffcef0) at kernel/qcoreapplication.cpp:1072
#11 0x00007ffff5234679 in QApplicationPrivate::notify_helper (this=this@entry=0x63aa60, receiver=receiver@entry=0x860a50, e=e@entry=0x7fffffffcef0)
    at kernel/qapplication.cpp:3713
#12 0x00007ffff523b90a in QApplication::notify (this=0x7fffffffd3d0, receiver=0x860a50, e=0x7fffffffcef0) at kernel/qapplication.cpp:3682
#13 0x00007ffff49b079b in QCoreApplication::notifyInternal (this=0x7fffffffd3d0, receiver=receiver@entry=0x860a50, event=event@entry=0x7fffffffcef0)
    at kernel/qcoreapplication.cpp:965
#14 0x00007ffff526ed88 in sendEvent (event=0x7fffffffcef0, receiver=0x860a50) at ../../include/QtCore/../../src/corelib/kernel/qcoreapplication.h:224
#15 QWidgetPrivate::sendPendingMoveAndResizeEvents (this=this@entry=0x808600, recursive=recursive@entry=false, disableUpdates=disableUpdates@entry=false)
    at kernel/qwidget.cpp:7699
#16 0x00007ffff5272b48 in QWidgetPrivate::show_helper (this=this@entry=0x808600) at kernel/qwidget.cpp:7750
#17 0x00007ffff527567c in QWidget::setVisible (this=0x860a50, visible=<optimized out>) at kernel/qwidget.cpp:8095
#18 0x00007ffff5272920 in QWidget::show (this=this@entry=0x860a50) at kernel/qwidget.cpp:7657
#19 0x00007ffff5272aee in QWidgetPrivate::showChildren (this=this@entry=0x81df10, spontaneous=spontaneous@entry=false) at kernel/qwidget.cpp:8178
#20 0x00007ffff5272b67 in QWidgetPrivate::show_helper (this=this@entry=0x81df10) at kernel/qwidget.cpp:7756
#21 0x00007ffff527567c in QWidget::setVisible (this=0x84abf0, visible=<optimized out>) at kernel/qwidget.cpp:8095
#22 0x00007ffff5272920 in QWidget::show (this=this@entry=0x84abf0) at kernel/qwidget.cpp:7657
#23 0x00007ffff5272aee in QWidgetPrivate::showChildren (this=this@entry=0x70d540, spontaneous=spontaneous@entry=false) at kernel/qwidget.cpp:8178
#24 0x00007ffff5272b67 in QWidgetPrivate::show_helper (this=this@entry=0x70d540) at kernel/qwidget.cpp:7756
#25 0x00007ffff527567c in QWidget::setVisible (this=0x717350, visible=<optimized out>) at kernel/qwidget.cpp:8095
#26 0x00007ffff5272920 in QWidget::show (this=0x717350) at kernel/qwidget.cpp:7657
#27 0x000000000042c79e in main (argc=1, argv=0x7fffffffd508) at kmines-15.08.0/main.cpp:81