fix: deal with null objects in errors in Form.filterErrorsBasedOnSche…

…ma() (#4310)

* fix: deal with null objects in errors in Form.filterErrorsBasedOnSchema()
Fixes #4306 by using `lodash.isNil()` instead of comparing to `undefined`
- Updated `Form.filterErrorsBasedOnSchema()` to use lodash `isNil()` to check if the key is either null or undefined
- Updated the `CHANGELOG.md` accordingly

* - Made name more correct

CHANGELOG.md

@@ -21,6 +21,7 @@ should change the heading of the (upcoming) version to include a major version b
 ## @rjsf/core
 
 - Updated `SchemaField` to pass `required` flag to `_AnyOfField`/`_OneOfField`
+- Updated `Form` to deal with null objects in `filterErrorsBasedOnSchema()`, fixing [#4306](https://github.com/rjsf-team/react-jsonschema-form/issues/4306)
 
 ## Dev / docs / playground
 

packages/core/src/components/Form.tsx

@@ -37,6 +37,7 @@ import {
 import _forEach from 'lodash/forEach';
 import _get from 'lodash/get';
 import _isEmpty from 'lodash/isEmpty';
+import _isNil from 'lodash/isNil';
 import _pick from 'lodash/pick';
 import _toPath from 'lodash/toPath';
 
@@ -603,18 +604,18 @@ export default class Form<
     if (resolvedSchema?.type !== 'object' && resolvedSchema?.type !== 'array') {
       filteredErrors.__errors = schemaErrors.__errors;
     }
-    // Removing undefined and empty errors.
-    const filterUndefinedErrors = (errors: any): ErrorSchema<T> => {
+    // Removing undefined, null and empty errors.
+    const filterNilOrEmptyErrors = (errors: any): ErrorSchema<T> => {
       _forEach(errors, (errorAtKey, errorKey: keyof typeof errors) => {
-        if (errorAtKey === undefined) {
+        if (_isNil(errorAtKey)) {
           delete errors[errorKey];
         } else if (typeof errorAtKey === 'object' && !Array.isArray(errorAtKey.__errors)) {
-          filterUndefinedErrors(errorAtKey);
+          filterNilOrEmptyErrors(errorAtKey);
         }
       });
       return errors;
     };
-    return filterUndefinedErrors(filteredErrors);
+    return filterNilOrEmptyErrors(filteredErrors);
   }
 
   /** Function to handle changes made to a field in the `Form`. This handler receives an entirely new copy of the