Fixes issues with cleaning broken Markdown blocks and reduce words to…

assets/stylesheets/common/markdown-shims.scss

@@ -8,3 +8,7 @@ pre:has(> code) + br {
 aside.quote + br {
   display: none;
 }
+
+:is(ul, ol, blockquote) + br:has(+ ul, + ol, + blockquote) {
+  display: none;
+}

bbcode-src/plugins/lineBreak.js

@@ -27,6 +27,7 @@ const walk = (t, disableLineBreakConversion = false) => {
   const tree = t;
 
   if (Array.isArray(tree)) {
+    reduceWordsToLines(tree);
     if (tree.some(isString)) {
       // array contains strings. Might be md compatible
       tree.unshift(MD_NEWLINE_INJECT);
@@ -69,6 +70,36 @@ const walk = (t, disableLineBreakConversion = false) => {
   return tree;
 };
 
+/**
+ * Reduces the list into lines, so that we can process them by line.
+ * Performs in place.
+ * @param {(string|Object)[]} words
+ */
+const reduceWordsToLines = (words) => {
+  let rightIdx = words.findLastIndex((w) => isString(w) && !isEOL(w)) + 1;
+
+  for (let i = rightIdx - 1; i >= 0; i--) {
+    if (isString(words[i]) && !isEOL(words[i])) {
+      continue;
+    }
+    if (isEOL(words[i])) {
+      words.splice(i + 1, rightIdx - i - 1, words.slice(i + 1, rightIdx).join(""));
+      rightIdx = i;
+      continue;
+    }
+    if (isObj(words[i])) {
+      if (i !== rightIdx - 1) {
+        words.splice(i + 1, rightIdx - i - 1, words.slice(i + 1, rightIdx).join(""));
+      }
+      rightIdx = i;
+    }
+  }
+
+  if (0 !== rightIdx) {
+    words.splice(0, rightIdx - 1, words.slice(0, rightIdx).join(""));
+  }
+};
+
 /**
  * Converts `\n` to `<br/>` self closing tag. Supply this as the last plugin in the preset lists
  *

bbcode-src/utils/common.js

@@ -121,6 +121,10 @@ const ESCAPABLES_REGEX =
   /((\n|^)(?<fence>```+|~~~+)(?<fenceInfo>.*\n))|(?<bbcode>\[(?<bbcodeTag>i?code|plain)(=.*)?\])|(?<backtick>(?<tickStart>`{1,2})(.*)(?<tickEnd>\k<tickStart>))/im;
 const MD_TABLE_REGEX = /^(\|[^\n]+\|\r?\n)((?:\| ?:?[-]+:? ?)+\|)(\n(?:\|[^\n]+\|\r?\n?)*)?$/m;
 
+const MD_BROKEN_ORDERED_LIST = "</ol>\n<br><ol>";
+const MD_BROKEN_UNORDERED_LIST = "</ul>\n<br><ul>";
+const MD_BROKEN_BLOCKQUOTE = "</blockquote>\n<blockquote>";
+
 /**
  * Generates a random GUID.
  *
@@ -156,4 +160,7 @@ export {
   MD_TABLE_REGEX,
   URL_REGEX_SINGLE_LINE,
   ESCAPABLES_REGEX,
+  MD_BROKEN_ORDERED_LIST,
+  MD_BROKEN_UNORDERED_LIST,
+  MD_BROKEN_BLOCKQUOTE,
 };

bbcode-src/utils/postprocess.js

@@ -1,4 +1,11 @@
-import { MD_NEWLINE_INJECT, MD_NEWLINE_INJECT_COMMENT, MD_NEWLINE_PRE_INJECT } from "./common";
+import {
+  MD_BROKEN_BLOCKQUOTE,
+  MD_BROKEN_ORDERED_LIST,
+  MD_BROKEN_UNORDERED_LIST,
+  MD_NEWLINE_INJECT,
+  MD_NEWLINE_INJECT_COMMENT,
+  MD_NEWLINE_PRE_INJECT,
+} from "./common";
 
 /**
  * Post Processing designed to fix issues with Markdown and BBCode that the parser can't fix.
@@ -17,6 +24,14 @@ function removeNewlineInjects(raw) {
   return processed;
 }
 
+function cleanMultilineMDBlocks(raw) {
+  const processed = raw
+    .replaceAll(MD_BROKEN_ORDERED_LIST, "")
+    .replaceAll(MD_BROKEN_UNORDERED_LIST, "")
+    .replaceAll(MD_BROKEN_BLOCKQUOTE, "");
+  return processed;
+}
+
 /**
  * Injects hoisted code blocks back into the raw string
  * @param {string} raw input to inject hoisted code blocks into
@@ -81,6 +96,7 @@ export function postprocess(raw, data) {
     removeNewlineInjects,
     createClassStyleTagTemplate,
     createScriptTagTemplate,
+    cleanMultilineMDBlocks,
     renderHoistedCodeBlocks,
   ];
   for (const postprocessor of postprocessors) {