Fix crash in attribute form after adding field

nyalldawson · nyalldawson · commit 3d009f9a6be6 · 2018-03-22T16:26:02.000+10:00
Fixes #18507 (cherry-picked from c8f5979)
diff --git a/src/gui/qgsattributeform.cpp b/src/gui/qgsattributeform.cpp
@@ -1099,6 +1099,7 @@ void QgsAttributeForm::init()
   vl->addWidget( container );
 
   mFormEditorWidgets.clear();
+  mFormWidgets.clear();
 
   // a bar to warn the user with non-blocking messages
   setContentsMargins( 0, 0, 0, 0 );
