src/components/Panel.tsx

@@ -88,7 +88,6 @@ export function Panel({ options, data, width, height, timeRange, onChangeTimeRan
         if (!additionalInfoConfig.value?.useMetric) {
           value = additionalInfoConfig.value.value;
         } else {
-          if (!_.isEmpty(additionalInfoConfig.value.metricName)) {
           const aggregatedValue = getLastMetricValue(
             grafanaSeriesList,
             additionalInfoConfig.value.metricName,
@@ -96,7 +95,6 @@ export function Panel({ options, data, width, height, timeRange, onChangeTimeRan
           );
           value = aggregatedValue !== null ? aggregatedValue : undefined;
         }
-        }
 
         additionalInfo = (
           <div

src/components/editors/ThresholdsEditor.tsx

@@ -1,5 +1,7 @@
 import { FieldNamePicker } from '../../grafana/MatchersUI/FieldNamePicker';
 
+import { isNumber } from '../../utils';
+
 import { GrafanaTheme, StandardEditorProps } from '@grafana/data';
 import {
   Button,
@@ -97,7 +99,7 @@ export function ThresholdsEditor({ onChange, value, context }: StandardEditorPro
                   <InlineField label="Use metric">
                     <InlineSwitch
                       value={threshold.useMetric}
-                      onChange={(evt) => onThresholdFieldChange(thresholdIdx, 'useMetric', (evt.target as any).checked)}
+                      onChange={(evt) => onThresholdFieldChange(thresholdIdx, 'useMetric', evt.currentTarget.checked)}
                     />
                   </InlineField>
                   <InlineField>
@@ -113,7 +115,7 @@ export function ThresholdsEditor({ onChange, value, context }: StandardEditorPro
                         placeholder="value"
                         width={24}
                         value={threshold.value}
-                        onChange={(evt) => onThresholdFieldChange(thresholdIdx, 'value', (evt.target as any).value)}
+                        onChange={(evt) => onThresholdFieldChange(thresholdIdx, 'value', isNumber(evt.currentTarget.value) ? +evt.currentTarget.value : undefined)}
                       />
                     )}
                   </InlineField>

src/components/editors/UseMetricEditor.tsx

@@ -1,5 +1,7 @@
 import { FieldNamePicker } from '../../grafana/MatchersUI/FieldNamePicker';
 
+import { isNumber } from '../../utils';
+
 import { StandardEditorProps } from '@grafana/data';
 import { HorizontalGroup, InlineField, InlineSwitch, Input } from '@grafana/ui';
 
@@ -32,7 +34,7 @@ export function UseMetricEditor({ onChange, value, context }: StandardEditorProp
       <InlineField label="Use metric">
         <InlineSwitch
           value={config?.useMetric}
-          onChange={(evt) => onFieldChange('useMetric', (evt.target as any).checked)}
+          onChange={(evt) => onFieldChange('useMetric', evt.currentTarget.checked)}
         />
       </InlineField>
       <InlineField>
@@ -48,7 +50,7 @@ export function UseMetricEditor({ onChange, value, context }: StandardEditorProp
             placeholder="value"
             value={config?.value}
             width={24}
-            onChange={(evt) => onFieldChange('value', (evt.target as any).value)}
+            onChange={(evt) => onFieldChange('value', isNumber(evt.currentTarget.value) ? +evt.currentTarget.value : undefined)}
           />
         )}
       </InlineField>

src/utils.ts

@@ -26,6 +26,9 @@ export function getLastMetricValue(
   metricName: string | undefined,
   optionName: string
 ): number | null {
+  if(metricName === undefined) {
+    return null;
+  }
   // optionName -> helper in Error, mb use option path instead
   const filteredSeries = filterMetricListByAlias(grafanaSeriesList, metricName, optionName);
   const serie = filteredSeries[0];
@@ -66,3 +69,7 @@ export function getAggregatedValueFromSerie(
       throw new Error(`Unknown aggregation type: ${aggregation}`);
   }
 }
+
+export function isNumber(value: string): boolean {
+  return !isNaN(parseFloat(value)) && isFinite(value as unknown as number);
+}