Add error handling for undefined extractors in language resolution

lib/entry-points.js

@@ -154094,7 +154094,13 @@ async function getCodeQLForCmd(cmd, checkVersion) {
     },
     async resolveExtractor(language) {
       const output = await this.resolveLanguages();
-      return output.extractors[language][0].extractor_root;
+      const extractors = output.extractors[language];
+      if (extractors === void 0) {
+        throw new Error(
+          `Unable to resolve an extractor for the language '${language}'.`
+        );
+      }
+      return extractors[0].extractor_root;
     },
     async resolveQueriesStartingPacks(queries) {
       const codeqlArgs = [