add backticks around the concrete parse error

Author: erik-krogh

javascript/extractor/src/com/semmle/js/extractor/AutoBuild.java

@@ -1236,8 +1236,8 @@ private void doExtract(FileExtractor extractor, Path file, ExtractorState state)
       if (!extractor.getConfig().isExterns()) seenFiles = true;
       List<ParseError> errors = loc == null ? Collections.emptyList() : loc.getParseErrors();
       for (ParseError err : errors) {
-        String msg = "A parse error occurred: " + StringUtil.escapeMarkdown(err.getMessage())
-            + ". Check the syntax of the file. If the file is invalid, correct the error or [exclude](https://docs.github.com/en/code-security/code-scanning/automatically-scanning-your-code-for-vulnerabilities-and-errors/customizing-code-scanning) the file from analysis.";
+        String msg = "A parse error occurred: `" + StringUtil.escapeMarkdown(err.getMessage()).trim()
+            + "`. Check the syntax of the file. If the file is invalid, correct the error or [exclude](https://docs.github.com/en/code-security/code-scanning/automatically-scanning-your-code-for-vulnerabilities-and-errors/customizing-code-scanning) the file from analysis.";
         // file, relative to the source root
         String relativeFilePath = null;
         if (file.startsWith(LGTM_SRC)) {

javascript/ql/integration-tests/all-platforms/diagnostics/syntax-error/diagnostics.expected

@@ -6,7 +6,7 @@
     "startColumn": 4,
     "startLine": 1
   },
-  "markdownMessage": "A parse error occurred: Unexpected token. Check the syntax of the file. If the file is invalid, correct the error or [exclude](https://docs.github.com/en/code-security/code-scanning/automatically-scanning-your-code-for-vulnerabilities-and-errors/customizing-code-scanning) the file from analysis.",
+  "markdownMessage": "A parse error occurred: `Unexpected token`. Check the syntax of the file. If the file is invalid, correct the error or [exclude](https://docs.github.com/en/code-security/code-scanning/automatically-scanning-your-code-for-vulnerabilities-and-errors/customizing-code-scanning) the file from analysis.",
   "severity": "warning",
   "source": {
     "extractorName": "javascript",