fix: handle nonexistent field: value

Author: khaaleoo

src/utils.ts

@@ -14,7 +14,7 @@ const groupBlockContent = (blockMap: BlockMapType): string[][] => {
   let index = -1;
 
   Object.keys(blockMap).forEach(id => {
-    blockMap[id].value.content?.forEach(blockId => {
+    blockMap[id].value?.content?.forEach(blockId => {
       const blockType = blockMap[blockId]?.value?.type;
 
       if (blockType && blockType !== lastType) {