Forbid default value nullification for non-nullable field (#6258)

as per title 


https://github.com/user-attachments/assets/ce07d437-eeeb-488c-8dfa-3fc07316f485

packages/twenty-server/src/engine/metadata-modules/field-metadata/utils/__tests__/assert-does-not-nullify-default-value-for-non-nullable-field.spec.ts

@@ -0,0 +1,38 @@
+import { assertDoesNotNullifyDefaultValueForNonNullableField } from 'src/engine/metadata-modules/field-metadata/utils/assert-does-not-nullify-default-value-for-non-nullable-field.util';
+
+describe('assertDoesNotNullifyDefaultValueForNonNullableField', () => {
+  it('should not throw if default value is set to null and field is nullable', () => {
+    expect(() =>
+      assertDoesNotNullifyDefaultValueForNonNullableField({
+        isNullable: true,
+        defaultValueFromUpdate: null,
+      }),
+    ).not.toThrow();
+  });
+
+  it('should not throw if default value is undefined and field is non nullable', () => {
+    expect(() =>
+      assertDoesNotNullifyDefaultValueForNonNullableField({
+        isNullable: false,
+      }),
+    ).not.toThrow();
+  });
+
+  it('should not throw if default value is not set to null and field is non nullable', () => {
+    expect(() =>
+      assertDoesNotNullifyDefaultValueForNonNullableField({
+        isNullable: false,
+        defaultValueFromUpdate: 'new default value',
+      }),
+    ).not.toThrow();
+  });
+
+  it('should throw if default value is set to null and field is non nullable', () => {
+    expect(() =>
+      assertDoesNotNullifyDefaultValueForNonNullableField({
+        isNullable: false,
+        defaultValueFromUpdate: null,
+      }),
+    ).toThrow();
+  });
+});

packages/twenty-server/src/engine/metadata-modules/field-metadata/utils/assert-does-not-nullify-default-value-for-non-nullable-field.util.ts

@@ -0,0 +1,19 @@
+import {
+  FieldMetadataException,
+  FieldMetadataExceptionCode,
+} from 'src/engine/metadata-modules/field-metadata/field-metadata.exception';
+
+export const assertDoesNotNullifyDefaultValueForNonNullableField = ({
+  isNullable,
+  defaultValueFromUpdate,
+}: {
+  isNullable: boolean;
+  defaultValueFromUpdate?: any;
+}) => {
+  if (!isNullable && defaultValueFromUpdate === null) {
+    throw new FieldMetadataException(
+      'Default value cannot be nullified for non-nullable field',
+      FieldMetadataExceptionCode.INVALID_FIELD_INPUT,
+    );
+  }
+};