fix(utils): Normalize undefined to undefined instead of "[undefined]" (#8017)

Author: Luca Forstner

packages/browser-integration-tests/suites/public-api/setContext/multiple_contexts/test.ts

@@ -16,7 +16,6 @@ sentryTest('should record multiple contexts', async ({ getLocalTestPath, page })
       baz: { qux: 'quux' },
     },
     context_2: { 1: 'foo', bar: false },
-    context_4: '[undefined]',
     context_5: '[NaN]',
     context_6: 3.141592653589793,
   });

packages/replay/test/unit/coreHandlers/util/addBreadcrumbEvent.test.ts

@@ -39,7 +39,7 @@ describe('Unit | coreHandlers | util | addBreadcrumbEvent', function () {
             category: 'console',
             message: 'Test message',
             thisIsNull: null,
-            thisIsUndefined: '[undefined]',
+            thisIsUndefined: undefined,
             circular: '[Circular ~]',
             timestamp: BASE_TIMESTAMP / 1000,
           },

packages/utils/src/normalize.ts

@@ -79,7 +79,10 @@ function visit(
   const [memoize, unmemoize] = memo;
 
   // Get the simple cases out of the way first
-  if (value === null || (['number', 'boolean', 'string'].includes(typeof value) && !isNaN(value))) {
+  if (
+    value == null || // this matches null and undefined -> eqeq not eqeqeq
+    (['number', 'boolean', 'string'].includes(typeof value) && !isNaN(value))
+  ) {
     return value as Primitive;
   }
 
@@ -220,11 +223,6 @@ function stringifyValue(
       return '[NaN]';
     }
 
-    // this catches `undefined` (but not `null`, which is a primitive and can be serialized on its own)
-    if (value === void 0) {
-      return '[undefined]';
-    }
-
     if (typeof value === 'function') {
       return `[Function: ${getFunctionName(value)}]`;
     }

packages/utils/test/normalize.test.ts

@@ -14,6 +14,7 @@ describe('normalize()', () => {
       expect(normalize(42)).toEqual(42);
       expect(normalize(true)).toEqual(true);
       expect(normalize(null)).toEqual(null);
+      expect(normalize(undefined)).toBeUndefined();
     });
 
     test('return same object or arrays for referenced inputs', () => {
@@ -403,7 +404,6 @@ describe('normalize()', () => {
 
   describe('changes unserializeable/global values/classes to their respective string representations', () => {
     test('primitive values', () => {
-      expect(normalize(undefined)).toEqual('[undefined]');
       expect(normalize(NaN)).toEqual('[NaN]');
       expect(normalize(Symbol('dogs'))).toEqual('[Symbol(dogs)]');
       // `BigInt` doesn't exist in Node 8
@@ -425,28 +425,26 @@ describe('normalize()', () => {
     });
 
     test('primitive values in objects/arrays', () => {
-      expect(normalize(['foo', 42, undefined, NaN])).toEqual(['foo', 42, '[undefined]', '[NaN]']);
+      expect(normalize(['foo', 42, NaN])).toEqual(['foo', 42, '[NaN]']);
       expect(
         normalize({
           foo: 42,
-          bar: undefined,
-          baz: NaN,
+          bar: NaN,
         }),
       ).toEqual({
         foo: 42,
-        bar: '[undefined]',
-        baz: '[NaN]',
+        bar: '[NaN]',
       });
     });
 
     test('primitive values in deep objects/arrays', () => {
-      expect(normalize(['foo', 42, [[undefined]], [NaN]])).toEqual(['foo', 42, [['[undefined]']], ['[NaN]']]);
+      expect(normalize(['foo', 42, [[undefined]], [NaN]])).toEqual(['foo', 42, [[undefined]], ['[NaN]']]);
       expect(
         normalize({
           foo: 42,
           bar: {
             baz: {
-              quz: undefined,
+              quz: null,
             },
           },
           wat: {
@@ -457,7 +455,7 @@ describe('normalize()', () => {
         foo: 42,
         bar: {
           baz: {
-            quz: '[undefined]',
+            quz: null,
           },
         },
         wat: {