chore: address security alerts on braces escape and KaTeX (#3301)

web/app/components/base/prompt-editor/plugins/variable-value-block/index.tsx

@@ -31,7 +31,7 @@ const VariableValueBlock = () => {
     if (matchArr === null)
       return null
 
-    const hashtagLength = matchArr[3].length + 4
+    const hashtagLength = matchArr[0].length
     const startOffset = matchArr.index
     const endOffset = startOffset + hashtagLength
     return {

web/app/components/base/prompt-editor/plugins/variable-value-block/utils.ts

@@ -1,5 +1,5 @@
 export function getHashtagRegexString(): string {
-  const hashtag = '(\{)(\{)([a-zA-Z_][a-zA-Z0-9_]{0,29})(\})(\})'
+  const hashtag = '\\{\\{[a-zA-Z_][a-zA-Z0-9_]{0,29}\\}\\}'
 
   return hashtag
 }