Fix deselecting lists. (#6080)

Co-authored-by: Víctor Fernández de Alba <[email protected]>

packages/volto-slate/news/6080.bugfix

@@ -0,0 +1 @@
+Fix removal of slate formatting applied to text when toggling the list buttons @robgietema

packages/volto-slate/src/utils/blocks.js

@@ -264,7 +264,7 @@ export const toggleBlock = (editor, format, allowedChildren) => {
   } else if (!isListItem && !wantsList) {
     toggleFormat(editor, format, allowedChildren);
   } else if (isListItem && wantsList && isActive) {
-    clearFormatting(editor);
+    clearList(editor);
   } else {
     console.warn('toggleBlock case not covered, please examine:', {
       wantsList,
@@ -298,6 +298,21 @@ export const switchListType = (editor, format) => {
   Transforms.wrapNodes(editor, block);
 };
 
+/*
+ * Clear list by exploding the block
+ */
+export const clearList = (editor) => {
+  const { slate } = config.settings;
+  Transforms.unwrapNodes(editor, {
+    match: (n) => slate.listTypes.includes(n.type),
+    split: true,
+  });
+  Transforms.setNodes(editor, {
+    type: 'p',
+  });
+  Editor.normalize(editor);
+};
+
 export const changeBlockToList = (editor, format) => {
   const { slate } = config.settings;
   const [match] = Editor.nodes(editor, {