Annotations: check for null or undefined fields before conversion (#27712)

public/app/features/annotations/standardAnnotationSupport.test.ts

@@ -5,9 +5,9 @@ describe('DataFrame to annotations', () => {
   test('simple conversion', () => {
     const frame = toDataFrame({
       fields: [
-        { type: FieldType.time, values: [1, 2, 3] },
-        { name: 'first string field', values: ['t1', 't2', 't3'] },
-        { name: 'tags', values: ['aaa,bbb', 'bbb,ccc', 'zyz'] },
+        { type: FieldType.time, values: [1, 2, 3, 4, 5] },
+        { name: 'first string field', values: ['t1', 't2', 't3', null, undefined] },
+        { name: 'tags', values: ['aaa,bbb', 'bbb,ccc', 'zyz', null, undefined] },
       ],
     });
 
@@ -37,6 +37,12 @@ describe('DataFrame to annotations', () => {
           "text": "t3",
           "time": 3,
         },
+        Object {
+          "time": 4,
+        },
+        Object {
+          "time": 5,
+        },
       ]
     `);
   });

public/app/features/annotations/standardAnnotationSupport.ts

@@ -175,8 +175,8 @@ export function getAnnotationsFromData(data: DataFrame[], options?: AnnotationEv
         }
       }
 
-      if (v !== undefined) {
-        if (f.split) {
+      if (!(v === null || v === undefined)) {
+        if (v && f.split) {
           v = (v as string).split(',');
         }
         (anno as any)[f.key] = v;