Fix issues with basic widget rendering and editing

lib/widgets/delegate.dart

@@ -14,7 +14,7 @@ abstract class EditorTextSelectionGestureDetectorBuilderDelegate {
 
   bool getForcePressEnabled();
 
-  bool? getSelectionEnabled();
+  bool getSelectionEnabled();
 }
 
 class EditorTextSelectionGestureDetectorBuilder {
@@ -43,7 +43,7 @@ class EditorTextSelectionGestureDetectorBuilder {
   onForcePressStart(ForcePressDetails details) {
     assert(delegate.getForcePressEnabled());
     shouldShowSelectionToolbar = true;
-    if (delegate.getSelectionEnabled()!) {
+    if (delegate.getSelectionEnabled()) {
       getRenderEditor()!.selectWordsInRange(
         details.globalPosition,
         null,
@@ -65,7 +65,7 @@ class EditorTextSelectionGestureDetectorBuilder {
   }
 
   onSingleTapUp(TapUpDetails details) {
-    if (delegate.getSelectionEnabled()!) {
+    if (delegate.getSelectionEnabled()) {
       getRenderEditor()!.selectWordEdge(SelectionChangedCause.tap);
     }
   }
@@ -73,7 +73,7 @@ class EditorTextSelectionGestureDetectorBuilder {
   onSingleTapCancel() {}
 
   onSingleLongTapStart(LongPressStartDetails details) {
-    if (delegate.getSelectionEnabled()!) {
+    if (delegate.getSelectionEnabled()) {
       getRenderEditor()!.selectPositionAt(
         details.globalPosition,
         null,
@@ -83,7 +83,7 @@ class EditorTextSelectionGestureDetectorBuilder {
   }
 
   onSingleLongTapMoveUpdate(LongPressMoveUpdateDetails details) {
-    if (delegate.getSelectionEnabled()!) {
+    if (delegate.getSelectionEnabled()) {
       getRenderEditor()!.selectPositionAt(
         details.globalPosition,
         null,
@@ -99,7 +99,7 @@ class EditorTextSelectionGestureDetectorBuilder {
   }
 
   onDoubleTapDown(TapDownDetails details) {
-    if (delegate.getSelectionEnabled()!) {
+    if (delegate.getSelectionEnabled()) {
       getRenderEditor()!.selectWord(SelectionChangedCause.tap);
       if (shouldShowSelectionToolbar) {
         getEditor()!.showToolbar();

lib/widgets/editor.dart

@@ -269,10 +269,10 @@ class _QuillEditorState extends State<QuillEditor>
           widget.placeholder,
           widget.onLaunchUrl,
           ToolbarOptions(
-            copy: widget.enableInteractiveSelection ?? true,
-            cut: widget.enableInteractiveSelection ?? true,
-            paste: widget.enableInteractiveSelection ?? true,
-            selectAll: widget.enableInteractiveSelection ?? true,
+            copy: widget.enableInteractiveSelection,
+            cut: widget.enableInteractiveSelection,
+            paste: widget.enableInteractiveSelection,
+            selectAll: widget.enableInteractiveSelection,
           ),
           theme.platform == TargetPlatform.iOS ||
               theme.platform == TargetPlatform.android,
@@ -295,7 +295,7 @@ class _QuillEditorState extends State<QuillEditor>
           selectionColor,
           textSelectionControls,
           widget.keyboardAppearance,
-          widget.enableInteractiveSelection ?? true,
+          widget.enableInteractiveSelection,
           widget.scrollPhysics,
           widget.embedBuilder),
     );
@@ -330,7 +330,7 @@ class _QuillEditorSelectionGestureDetectorBuilder
   @override
   onForcePressStart(ForcePressDetails details) {
     super.onForcePressStart(details);
-    if (delegate.getSelectionEnabled()! && shouldShowSelectionToolbar) {
+    if (delegate.getSelectionEnabled() && shouldShowSelectionToolbar) {
       getEditor()!.showToolbar();
     }
   }
@@ -498,7 +498,7 @@ class _QuillEditorSelectionGestureDetectorBuilder
 
   @override
   void onSingleLongTapStart(LongPressStartDetails details) {
-    if (delegate.getSelectionEnabled()!) {
+    if (delegate.getSelectionEnabled()) {
       switch (Theme.of(_state.context).platform) {
         case TargetPlatform.iOS:
         case TargetPlatform.macOS:

lib/widgets/raw_editor.dart

@@ -29,7 +29,6 @@ import 'delegate.dart';
 import 'editor.dart';
 import 'keyboard_listener.dart';
 
-
 class RawEditor extends StatefulWidget {
   final QuillController controller;
   final FocusNode focusNode;
@@ -1177,4 +1176,4 @@ class _Editor extends MultiChildRenderObjectWidget {
     renderObject.onSelectionChanged = onSelectionChanged;
     renderObject.setPadding(padding);
   }
-}
+}

lib/widgets/text_block.dart

@@ -107,7 +107,7 @@ class EditableTextBlock extends StatelessWidget {
     int count = block.children.length;
     var children = <Widget>[];
     int index = 0;
-    for (Line line in block.children as Iterable<Line>) {
+    for (Line line in Iterable.castFrom<dynamic, Line>(block.children)) {
       index++;
       EditableTextLine editableTextLine = EditableTextLine(
           line,