fix(forms): Make multiline field utilities safe for undo actions

static/app/components/events/highlights/highlightsSettingsForm.tsx

@@ -77,8 +77,8 @@ export default function HighlightsSettingsForm({
             placeholder: t('environment, release, my-tag'),
             label: t('Highlighted Tags'),
             help: t('Separate tag keys with a newline.'),
-            getValue: val => extractMultilineFields(val),
-            setValue: val => convertMultilineFieldValue(val),
+            getValue: extractMultilineFields,
+            setValue: convertMultilineFieldValue,
           },
           {
             name: 'highlightContext',

static/app/data/forms/apiApplication.tsx

@@ -53,8 +53,8 @@ const forms: JsonFormObject[] = [
         placeholder: 'e.g. https://example.com/oauth/complete',
         label: 'Authorized Redirect URIs',
         help: 'Separate multiple entries with a newline.',
-        getValue: val => extractMultilineFields(val),
-        setValue: val => convertMultilineFieldValue(val),
+        getValue: extractMultilineFields,
+        setValue: convertMultilineFieldValue,
       },
       {
         name: 'allowedOrigins',
@@ -64,8 +64,8 @@ const forms: JsonFormObject[] = [
         placeholder: 'e.g. example.com',
         label: 'Authorized JavaScript Origins',
         help: 'Separate multiple entries with a newline.',
-        getValue: val => extractMultilineFields(val),
-        setValue: val => convertMultilineFieldValue(val),
+        getValue: extractMultilineFields,
+        setValue: convertMultilineFieldValue,
       },
     ],
   },

static/app/data/forms/organizationSecurityAndPrivacyGroups.tsx

@@ -158,8 +158,8 @@ const formGroups: JsonFormObject[] = [
         saveMessage: t(
           'Changes to your scrubbing configuration will apply to all new events.'
         ),
-        getValue: val => extractMultilineFields(val),
-        setValue: val => convertMultilineFieldValue(val),
+        getValue: extractMultilineFields,
+        setValue: convertMultilineFieldValue,
       },
       {
         name: 'safeFields',
@@ -183,8 +183,8 @@ const formGroups: JsonFormObject[] = [
         saveMessage: t(
           'Changes to your scrubbing configuration will apply to all new events.'
         ),
-        getValue: val => extractMultilineFields(val),
-        setValue: val => convertMultilineFieldValue(val),
+        getValue: extractMultilineFields,
+        setValue: convertMultilineFieldValue,
       },
       {
         name: 'scrubIPAddresses',

static/app/data/forms/projectGeneralSettings.tsx

@@ -152,27 +152,8 @@ export const fields = {
         </Hovercard>
       ),
     }),
-    getValue: (val: unknown) => {
-      if (typeof val === 'string') {
-        return extractMultilineFields(val);
-      }
-
-      if (Array.isArray(val) && val.every(item => typeof item === 'string')) {
-        return val;
-      }
-
-      return [];
-    },
-    setValue: (val: unknown) => {
-      if (
-        typeof val === 'string' ||
-        (Array.isArray(val) && val.every(item => typeof item === 'string'))
-      ) {
-        return convertMultilineFieldValue(val);
-      }
-
-      return '';
-    },
+    getValue: extractMultilineFields,
+    setValue: convertMultilineFieldValue,
   },
   scrapeJavaScript: {
     name: 'scrapeJavaScript',

static/app/data/forms/projectSecurityAndPrivacyGroups.tsx

@@ -169,8 +169,8 @@ const formGroups: JsonFormObject[] = [
         'aria-label': t(
           'Enter additional field names to match against when scrubbing data. Separate multiple entries with a newline'
         ),
-        getValue: val => extractMultilineFields(val),
-        setValue: val => convertMultilineFieldValue(val),
+        getValue: extractMultilineFields,
+        setValue: convertMultilineFieldValue,
       },
       {
         name: 'safeFields',
@@ -187,8 +187,8 @@ const formGroups: JsonFormObject[] = [
         'aria-label': t(
           'Enter field names which data scrubbers should ignore. Separate multiple entries with a newline'
         ),
-        getValue: val => extractMultilineFields(val),
-        setValue: val => convertMultilineFieldValue(val),
+        getValue: extractMultilineFields,
+        setValue: convertMultilineFieldValue,
       },
     ],
   },

static/app/data/forms/sentryApplication.tsx

@@ -1,7 +1,7 @@
 import {ExternalLink} from 'sentry/components/core/link';
 import type {Field} from 'sentry/components/forms/types';
 import {tct} from 'sentry/locale';
-import {extractMultilineFields} from 'sentry/utils';
+import {convertMultilineFieldValue, extractMultilineFields} from 'sentry/utils';
 
 const getPublicFormFields = (): Field[] => [
   {
@@ -113,9 +113,8 @@ const getPublicFormFields = (): Field[] => [
     placeholder: 'e.g. example.com',
     label: 'Authorized JavaScript Origins',
     help: 'Separate multiple entries with a newline.',
-    getValue: (val: string) => extractMultilineFields(val),
-    setValue: (val: string[] | undefined | null) =>
-      (val && typeof val.join === 'function' && val.join('\n')) || '',
+    getValue: extractMultilineFields,
+    setValue: convertMultilineFieldValue,
   },
 ];
 

static/app/utils.spec.tsx

@@ -1,4 +1,5 @@
 import {
+  convertMultilineFieldValue,
   descopeFeatureName,
   escapeDoubleQuotes,
   escapeIssueTagKey,
@@ -24,14 +25,10 @@ describe('utils.escapeIssueTagKey', () => {
 });
 
 describe('utils.extractMultilineFields', () => {
-  it('should work for basic, simple values', () => {
+  it('should split string by newlines', () => {
     expect(extractMultilineFields('one\ntwo\nthree')).toEqual(['one', 'two', 'three']);
   });
 
-  it('should return an empty array if only whitespace', () => {
-    expect(extractMultilineFields('    \n    \n\n\n   \n')).toEqual([]);
-  });
-
   it('should trim values and ignore empty lines', () => {
     expect(
       extractMultilineFields(
@@ -45,6 +42,36 @@ five`
       )
     ).toEqual(['one', 'two', 'three', 'four', 'five']);
   });
+
+  it('should return string array as-is', () => {
+    expect(extractMultilineFields(['one', 'two', 'three'])).toEqual([
+      'one',
+      'two',
+      'three',
+    ]);
+  });
+
+  it('should return empty array for invalid input', () => {
+    expect(extractMultilineFields(null)).toEqual([]);
+    expect(extractMultilineFields(undefined)).toEqual([]);
+    expect(extractMultilineFields(['one', 2, 'three'])).toEqual([]);
+  });
+});
+
+describe('utils.convertMultilineFieldValue', () => {
+  it('should return string as-is', () => {
+    expect(convertMultilineFieldValue('one\ntwo\nthree')).toBe('one\ntwo\nthree');
+  });
+
+  it('should join string array with newlines', () => {
+    expect(convertMultilineFieldValue(['one', 'two', 'three'])).toBe('one\ntwo\nthree');
+  });
+
+  it('should return empty string for invalid input', () => {
+    expect(convertMultilineFieldValue(null)).toBe('');
+    expect(convertMultilineFieldValue(undefined)).toBe('');
+    expect(convertMultilineFieldValue(['one', 2, 'three'])).toBe('');
+  });
 });
 
 describe('utils.explodeSlug', () => {

static/app/utils.tsx

@@ -41,30 +41,36 @@ export function percent(value: number, totalValue: number): number {
 }
 
 /**
- * Converts a multi-line textarea input value into an array,
- * eliminating empty lines
+ * Converts a multi-line textarea input value into an array, eliminating empty lines.
+ * Safely handles unknown input types for form field getValue callbacks.
  */
-export function extractMultilineFields(value: string): string[] {
-  return value
-    .split('\n')
-    .map(f => f.trim())
-    .filter(f => f !== '');
+export function extractMultilineFields(value: unknown): string[] {
+  // User input
+  if (typeof value === 'string') {
+    return value
+      .split('\n')
+      .map(f => f.trim())
+      .filter(f => f !== '');
+  }
+  // API response / undo form save action
+  if (Array.isArray(value) && value.every(item => typeof item === 'string')) {
+    return value;
+  }
+
+  return [];
 }
 
 /**
- * If the value is of type Array, converts it to type string, keeping the line breaks, if there is any
+ * Converts a value to a multi-line string for display in textarea.
+ * Safely handles unknown input types for form field setValue callbacks.
  */
-export function convertMultilineFieldValue<T extends string | string[]>(
-  value: T
-): string {
-  if (Array.isArray(value)) {
-    return value.join('\n');
-  }
-
+export function convertMultilineFieldValue(value: unknown): string {
   if (typeof value === 'string') {
-    return value.split('\n').join('\n');
+    return value;
+  }
+  if (Array.isArray(value) && value.every(item => typeof item === 'string')) {
+    return value.join('\n');
   }
-
   return '';
 }