QmakeProject: Don't crash on project import

Amends fc1fc6a07a.

Fixes: QTCREATORBUG-24802
Change-Id: I62e7e0bab82ae1b025c053785b77586aa78bcd1f
Reviewed-by: Christian Kandeler <christian.kandeler@qt.io>

src/plugins/qmakeprojectmanager/qmakestep.cpp

@@ -614,6 +614,7 @@ void QMakeStep::userArgumentsChanged()
 {
     if (m_ignoreChange)
         return;
+    if (qmakeAdditonalArgumentsLineEdit)
         qmakeAdditonalArgumentsLineEdit->setText(m_userArgs);
     updateAbiWidgets();
     updateEffectiveQMakeCall();
@@ -723,6 +724,9 @@ bool QMakeStep::isAndroidKit() const
 
 void QMakeStep::updateAbiWidgets()
 {
+    if (!abisLabel)
+        return;
+
     BaseQtVersion *qtVersion = QtKitAspect::qtVersion(target()->kit());
     if (!qtVersion)
         return;
@@ -762,6 +766,7 @@ void QMakeStep::updateAbiWidgets()
 
 void QMakeStep::updateEffectiveQMakeCall()
 {
+    if (qmakeArgumentsEdit)
         qmakeArgumentsEdit->setPlainText(effectiveQMakeCall());
 }