From 40d54df56746fe5e9fe5907bee389fc9b35b877c Mon Sep 17 00:00:00 2001
From: Andrew Henry <andrew.k.henry@nasa.gov>
Date: Mon, 8 Apr 2019 22:02:40 -0700
Subject: [PATCH] Summary widget unsubscribe (#2364)

* Delete subscription handle to prevent double unsubscribe error

* Do not attempt to render undefined telemetry datum
---
 src/plugins/summaryWidget/src/ConditionManager.js            | 1 +
 .../src/telemetry/SummaryWidgetTelemetryProvider.js          | 2 +-
 src/plugins/summaryWidget/src/views/SummaryWidgetView.js     | 5 ++++-
 3 files changed, 6 insertions(+), 2 deletions(-)

diff --git a/src/plugins/summaryWidget/src/ConditionManager.js b/src/plugins/summaryWidget/src/ConditionManager.js
index 120dd954ec..e9c18dce98 100644
--- a/src/plugins/summaryWidget/src/ConditionManager.js
+++ b/src/plugins/summaryWidget/src/ConditionManager.js
@@ -237,6 +237,7 @@ define ([
         });
         delete this.compositionObjs[objectId];
         this.subscriptions[objectId](); //unsubscribe from telemetry source
+        delete this.subscriptions[objectId];
         this.eventEmitter.emit('remove', identifier);
 
         if (_.isEmpty(this.compositionObjs)) {
diff --git a/src/plugins/summaryWidget/src/telemetry/SummaryWidgetTelemetryProvider.js b/src/plugins/summaryWidget/src/telemetry/SummaryWidgetTelemetryProvider.js
index 4f835dffcf..cd16974306 100644
--- a/src/plugins/summaryWidget/src/telemetry/SummaryWidgetTelemetryProvider.js
+++ b/src/plugins/summaryWidget/src/telemetry/SummaryWidgetTelemetryProvider.js
@@ -43,7 +43,7 @@ define([
         return evaluator.requestLatest(options)
             .then(function (latestDatum) {
                 this.pool.release(evaluator);
-                return [latestDatum];
+                return latestDatum ? [latestDatum] : [];
             }.bind(this));
     };
 
diff --git a/src/plugins/summaryWidget/src/views/SummaryWidgetView.js b/src/plugins/summaryWidget/src/views/SummaryWidgetView.js
index bfe73667ac..bc081f748e 100644
--- a/src/plugins/summaryWidget/src/views/SummaryWidgetView.js
+++ b/src/plugins/summaryWidget/src/views/SummaryWidgetView.js
@@ -52,7 +52,10 @@ define([
             strategy: 'latest',
             size: 1
         }).then(function (results) {
-            if (this.destroyed || this.hasUpdated || this.renderTracker !== renderTracker) {
+            if (this.destroyed ||
+                this.hasUpdated ||
+                this.renderTracker !== renderTracker ||
+                results.length === 0) {
                 return;
             }
             this.updateState(results[results.length - 1]);