#1357 Respect markdown code boundaries for code execution

- minor code changes

packages/coreutils/src/index.ts

@@ -16,4 +16,5 @@ export * from './url';
 export * from './uuid';
 export * from './vector';
 export * from './modeldb';
-export * from './markdowncodeblocks';
+export * from './markdowncodeblocks';
+

packages/coreutils/src/markdowncodeblocks.ts

@@ -31,6 +31,7 @@ namespace MarkdownCodeBlocks {
     constructor(startLine: number) {
       this.startLine = startLine;
       this.code = "";
+      this.endLine = -1;
     }
   }