Ensure queries[language] objects are initialized

src/analyze.ts

@@ -162,7 +162,10 @@ export async function runQueries(
     logger.startGroup(`Analyzing ${language}`);
 
     const queries = config.queries[language];
-    if (queries.builtin.length === 0 && queries.custom.length === 0) {
+    if (
+      queries === undefined ||
+      (queries.builtin.length === 0 && queries.custom.length === 0)
+    ) {
       throw new Error(
         `Unable to analyse ${language} as no queries were selected for this language`
       );

src/config-utils.test.ts

@@ -68,7 +68,10 @@ test("load empty config", async (t) => {
     const codeQL = setCodeQL({
       async resolveQueries() {
         return {
-          byLanguage: {},
+          byLanguage: {
+            javascript: { queries: ["query1.ql"] },
+            python: { queries: ["query2.ql"] },
+          },
           noDeclaredLanguage: {},
           multipleDeclaredLanguages: {},
         };
@@ -116,7 +119,10 @@ test("loading config saves config", async (t) => {
     const codeQL = setCodeQL({
       async resolveQueries() {
         return {
-          byLanguage: {},
+          byLanguage: {
+            javascript: { queries: ["query1.ql"] },
+            python: { queries: ["query2.ql"] },
+          },
           noDeclaredLanguage: {},
           multipleDeclaredLanguages: {},
         };