StatPanel: Fixes BizChart error max: yyy should not be less than min zzz (#28587)

packages/grafana-data/src/field/fieldOverrides.test.ts

@@ -11,14 +11,14 @@ import { MutableDataFrame, toDataFrame } from '../dataframe';
 import {
   DataFrame,
   Field,
+  FieldColorModeId,
   FieldConfig,
   FieldConfigPropertyItem,
   FieldConfigSource,
   FieldType,
   InterpolateFunction,
-  ThresholdsMode,
-  FieldColorModeId,
   ScopedVars,
+  ThresholdsMode,
 } from '../types';
 import { locationUtil, Registry } from '../utils';
 import { mockStandardProperties } from '../utils/tests/mockStandardProperties';
@@ -87,6 +87,21 @@ describe('Global MinMax', () => {
     expect(minmax.min).toEqual(-20);
     expect(minmax.max).toEqual(1234);
   });
+
+  describe('when value is null', () => {
+    it('then global min max should be null', () => {
+      const frame = toDataFrame({
+        fields: [
+          { name: 'Time', type: FieldType.time, values: [1] },
+          { name: 'Value', type: FieldType.number, values: [null] },
+        ],
+      });
+      const { min, max } = findNumericFieldMinMax([frame]);
+
+      expect(min).toBeNull();
+      expect(max).toBeNull();
+    });
+  });
 });
 
 describe('applyFieldOverrides', () => {

packages/grafana-data/src/field/fieldOverrides.ts

@@ -55,11 +55,23 @@ export function findNumericFieldMinMax(data: DataFrame[]): GlobalMinMax {
     for (const field of frame.fields) {
       if (field.type === FieldType.number) {
         const stats = reduceField({ field, reducers });
-        if (stats[ReducerID.min] < min) {
-          min = stats[ReducerID.min];
+        const statsMin = stats[ReducerID.min];
+        const statsMax = stats[ReducerID.max];
+
+        if (!statsMin) {
+          min = statsMin;
         }
-        if (stats[ReducerID.max] > max) {
-          max = stats[ReducerID.max];
+
+        if (!statsMax) {
+          max = statsMax;
+        }
+
+        if (statsMin && statsMin < min) {
+          min = statsMin;
+        }
+
+        if (statsMax && statsMax > max) {
+          max = statsMax;
         }
       }
     }