Make missing snippet message include languages (#2861)

![image](https://github.com/user-attachments/assets/9121b9e4-62dc-47e4-9668-e3fe661c5ed5)

Author: AndreasArvidsson

packages/cursorless-engine/src/core/getPreferredSnippet.ts

@@ -37,12 +37,22 @@ export function getPreferredSnippet(
   const preferredSnippet = filteredSnippets[0];
 
   if (preferredSnippet == null) {
-    throw new Error("No snippet available for the current language");
+    const languages = getUniqueLanguagesString(snippetDescription.snippets);
+    throw new Error(
+      `No snippet available for language '${languageId}'. Available languages: ${languages}`,
+    );
   }
 
   return preferredSnippet;
 }
 
+function getUniqueLanguagesString(snippets: CustomInsertSnippetArg[]): string {
+  const languages = new Set(
+    snippets.flatMap((snippet) => snippet.languages ?? []),
+  );
+  return Array.from(languages).sort().join(", ");
+}
+
 /**
  * Filter snippet definitions by language.
  * @param snippetDescriptions The snippets to filter