Throw a better error if database doesn't exist due to language mismatch

Author: shati-patel

lib/codeql.js

@@ -82,6 +82,7 @@ libraryPathDependencies: codeql-${language}`
 
 async function downloadDatabase(
   repoId: number,
+  repoName: string,
   language: string,
   signedAuthToken?: string,
   pat?: string
@@ -101,8 +102,13 @@ async function downloadDatabase(
     );
   } catch (error: any) {
     console.log("Error while downloading database");
-    if (error.httpStatusCode === 404) {
-      throw new Error("No database available.");
+    if (
+      error.httpStatusCode === 404 &&
+      error.httpMessage.includes("No database available for")
+    ) {
+      throw new Error(
+        `Language mismatch: The query targets ${language}, but the repository "${repoName}" has no CodeQL database available for that language.`
+      );
     } else {
       throw error;
     }

lib/codeql.js.map

@@ -21,6 +21,7 @@ export class HTTPError extends Error {
     this.httpMessage = httpMessage;
   }
 }
+
 const userAgent = "actions/tool-cache";
 
 /**

lib/download-database.js.map

@@ -43,6 +43,7 @@ async function run(): Promise<void> {
       console.log("Getting database");
       const dbZip = await downloadDatabase(
         repo.id,
+        repo.nwo,
         language,
         repo.token,
         repo.pat