telemetry.ts: send telemetry only if aiKey is not empty

Change-Id: Ic1fe3eb79f85d6a0eafea20dc7dc6e5d283d7ca4
diff --git a/src/telemetry.ts b/src/telemetry.ts
index 5f789aa..b06ae39 100644
--- a/src/telemetry.ts
+++ b/src/telemetry.ts
@@ -183,6 +183,9 @@
 	properties?: { [key: string]: string },
 	measures?: { [key: string]: number }
 ): void {
+	if (!aiKey) {
+		return;  // cannot enable telemetry
+	}
 	telemtryReporter = telemtryReporter
 		? telemtryReporter
 		: new TelemetryReporter(extensionId, extensionVersion, aiKey);