Add typing to readJsonlFile

We're still not verifying the actual object returned by JSON.parse so
this isn't any safer at runtime than using 'any', but it helps add more
static typing to the code calling readJsonlFile.

extensions/ql-vscode/src/common/jsonl-reader.ts

@@ -10,9 +10,9 @@ import { readFile } from "fs-extra";
  * @param path The path to the file.
  * @param handler Callback to be invoked for each top-level JSON object in order.
  */
-export async function readJsonlFile(
+export async function readJsonlFile<T>(
   path: string,
-  handler: (value: any) => Promise<void>,
+  handler: (value: T) => Promise<void>,
 ): Promise<void> {
   const logSummary = await readFile(path, "utf-8");
 
@@ -20,7 +20,7 @@ export async function readJsonlFile(
   const jsonSummaryObjects: string[] = logSummary.split(/\r?\n\r?\n/g);
 
   for (const obj of jsonSummaryObjects) {
-    const jsonObj = JSON.parse(obj);
+    const jsonObj = JSON.parse(obj) as T;
     await handler(jsonObj);
   }
 }

extensions/ql-vscode/src/log-insights/log-scanner.ts

@@ -103,7 +103,7 @@ export class EvaluationLogScannerSet {
       p.createScanner(problemReporter),
     );
 
-    await readJsonlFile(jsonSummaryLocation, async (obj) => {
+    await readJsonlFile<SummaryEvent>(jsonSummaryLocation, async (obj) => {
       scanners.forEach((scanner) => {
         scanner.onEvent(obj);
       });

extensions/ql-vscode/src/log-insights/log-summary-parser.ts

@@ -19,7 +19,7 @@ export async function parseViewerData(
 ): Promise<EvalLogData[]> {
   const viewerData: EvalLogData[] = [];
 
-  await readJsonlFile(jsonSummaryPath, async (jsonObj) => {
+  await readJsonlFile<EvalLogData>(jsonSummaryPath, async (jsonObj) => {
     // Only convert log items that have an RA and millis field
     if (jsonObj.ra !== undefined && jsonObj.millis !== undefined) {
       const newLogData: EvalLogData = {