Fix theming for error toasts (#160219)

## Summary

Fixes https://github.com/elastic/kibana/issues/159153.

Applies the current theme (dark/light) to error toasts.

Before:


![image](b0a05412-3e07-4980-b3e8-8dcdb602119f)

After:


![image](96bbaf58-25a6-47a3-b9ba-b3caf7a90cd9)

packages/core/notifications/core-notifications-browser-internal/src/notifications_service.ts

@@ -75,7 +75,8 @@ export class NotificationsService {
           title,
           error,
           openModal: overlays.openModal,
-          i18nContext: () => i18nDep.Context,
+          i18n: i18nDep,
+          theme,
         }),
     };
   }

packages/core/notifications/core-notifications-browser-internal/src/toasts/error_toast.test.tsx

@@ -11,6 +11,8 @@ import React from 'react';
 import { mountWithIntl } from '@kbn/test-jest-helpers';
 
 import { ErrorToast } from './error_toast';
+import { themeServiceMock } from '@kbn/core-theme-browser-mocks';
+import { i18nServiceMock } from '@kbn/core-i18n-browser-mocks';
 
 interface ErrorToastProps {
   error?: Error;
@@ -19,6 +21,8 @@ interface ErrorToastProps {
 }
 
 let openModal: jest.Mock;
+const mockTheme = themeServiceMock.createStartContract();
+const mockI18n = i18nServiceMock.createStartContract();
 
 beforeEach(() => (openModal = jest.fn()));
 
@@ -29,9 +33,8 @@ function render(props: ErrorToastProps = {}) {
       error={props.error || new Error('error message')}
       title={props.title || 'An error occured'}
       toastMessage={props.toastMessage || 'This is the toast message'}
-      i18nContext={() =>
-        ({ children }) =>
-          <React.Fragment>{children}</React.Fragment>}
+      i18n={mockI18n}
+      theme={mockTheme}
     />
   );
 }

packages/core/notifications/core-notifications-browser-internal/src/toasts/error_toast.tsx

@@ -22,13 +22,16 @@ import { EuiSpacer } from '@elastic/eui';
 import { FormattedMessage } from '@kbn/i18n-react';
 import type { I18nStart } from '@kbn/core-i18n-browser';
 import type { OverlayStart } from '@kbn/core-overlays-browser';
+import { ThemeServiceStart } from '@kbn/core-theme-browser';
+import { CoreContextProvider } from '@kbn/core-theme-browser-internal';
 
 interface ErrorToastProps {
   title: string;
   error: Error;
   toastMessage: string;
   openModal: OverlayStart['openModal'];
-  i18nContext: () => I18nStart['Context'];
+  i18n: I18nStart;
+  theme: ThemeServiceStart;
 }
 
 interface RequestError extends Error {
@@ -52,9 +55,9 @@ export function showErrorDialog({
   title,
   error,
   openModal,
-  i18nContext,
-}: Pick<ErrorToastProps, 'error' | 'title' | 'openModal' | 'i18nContext'>) {
-  const I18nContext = i18nContext();
+  i18n,
+  theme,
+}: Pick<ErrorToastProps, 'error' | 'title' | 'openModal' | 'i18n' | 'theme'>) {
   let text = '';
 
   if (isRequestError(error)) {
@@ -68,32 +71,30 @@ export function showErrorDialog({
 
   const modal = openModal(
     mount(
-      <React.Fragment>
-        <I18nContext>
-          <EuiModalHeader>
-            <EuiModalHeaderTitle>{title}</EuiModalHeaderTitle>
-          </EuiModalHeader>
-          <EuiModalBody data-test-subj="errorModalBody">
-            <EuiCallOut size="s" color="danger" iconType="error" title={error.message} />
-            {text && (
-              <React.Fragment>
-                <EuiSpacer size="s" />
-                <EuiCodeBlock isCopyable={true} paddingSize="s">
-                  {text}
-                </EuiCodeBlock>
-              </React.Fragment>
-            )}
-          </EuiModalBody>
-          <EuiModalFooter>
-            <EuiButton onClick={() => modal.close()} fill>
-              <FormattedMessage
-                id="core.notifications.errorToast.closeModal"
-                defaultMessage="Close"
-              />
-            </EuiButton>
-          </EuiModalFooter>
-        </I18nContext>
-      </React.Fragment>
+      <CoreContextProvider i18n={i18n} theme={theme}>
+        <EuiModalHeader>
+          <EuiModalHeaderTitle>{title}</EuiModalHeaderTitle>
+        </EuiModalHeader>
+        <EuiModalBody data-test-subj="errorModalBody">
+          <EuiCallOut size="s" color="danger" iconType="error" title={error.message} />
+          {text && (
+            <React.Fragment>
+              <EuiSpacer size="s" />
+              <EuiCodeBlock isCopyable={true} paddingSize="s">
+                {text}
+              </EuiCodeBlock>
+            </React.Fragment>
+          )}
+        </EuiModalBody>
+        <EuiModalFooter>
+          <EuiButton onClick={() => modal.close()} fill>
+            <FormattedMessage
+              id="core.notifications.errorToast.closeModal"
+              defaultMessage="Close"
+            />
+          </EuiButton>
+        </EuiModalFooter>
+      </CoreContextProvider>
     )
   );
 }
@@ -103,7 +104,8 @@ export function ErrorToast({
   error,
   toastMessage,
   openModal,
-  i18nContext,
+  i18n,
+  theme,
 }: ErrorToastProps) {
   return (
     <React.Fragment>
@@ -113,7 +115,7 @@ export function ErrorToast({
           size="s"
           color="danger"
           data-test-subj="errorToastBtn"
-          onClick={() => showErrorDialog({ title, error, openModal, i18nContext })}
+          onClick={() => showErrorDialog({ title, error, openModal, i18n, theme })}
         >
           <FormattedMessage
             id="core.toasts.errorToast.seeFullError"

packages/core/notifications/core-notifications-browser-internal/src/toasts/toasts_api.test.ts

@@ -12,6 +12,7 @@ import { ToastsApi } from './toasts_api';
 
 import { uiSettingsServiceMock } from '@kbn/core-ui-settings-browser-mocks';
 import { i18nServiceMock } from '@kbn/core-i18n-browser-mocks';
+import { themeServiceMock } from '@kbn/core-theme-browser-mocks';
 
 async function getCurrentToasts(toasts: ToastsApi) {
   return await firstValueFrom(toasts.get$());
@@ -41,7 +42,11 @@ function toastDeps() {
 }
 
 function startDeps() {
-  return { overlays: {} as any, i18n: i18nServiceMock.createStartContract() };
+  return {
+    overlays: {} as any,
+    i18n: i18nServiceMock.createStartContract(),
+    theme: themeServiceMock.createStartContract(),
+  };
 }
 
 describe('#get$()', () => {

packages/core/notifications/core-notifications-browser-internal/src/toasts/toasts_api.tsx

@@ -22,6 +22,7 @@ import type {
   ToastInputFields,
   ToastOptions,
 } from '@kbn/core-notifications-browser';
+import { ThemeServiceStart } from '@kbn/core-theme-browser';
 import { ErrorToast } from './error_toast';
 
 const normalizeToast = (toastOrTitle: ToastInput): ToastInputFields => {
@@ -44,15 +45,25 @@ export class ToastsApi implements IToasts {
 
   private overlays?: OverlayStart;
   private i18n?: I18nStart;
+  private theme?: ThemeServiceStart;
 
   constructor(deps: { uiSettings: IUiSettingsClient }) {
     this.uiSettings = deps.uiSettings;
   }
 
   /** @internal */
-  public start({ overlays, i18n }: { overlays: OverlayStart; i18n: I18nStart }) {
+  public start({
+    overlays,
+    i18n,
+    theme,
+  }: {
+    overlays: OverlayStart;
+    i18n: I18nStart;
+    theme: ThemeServiceStart;
+  }) {
     this.overlays = overlays;
     this.i18n = i18n;
+    this.theme = theme;
   }
 
   /** Observable of the toast messages to show to the user. */
@@ -176,7 +187,8 @@ export class ToastsApi implements IToasts {
           error={error}
           title={options.title}
           toastMessage={message}
-          i18nContext={() => this.i18n!.Context}
+          i18n={this.i18n!}
+          theme={this.theme!}
         />
       ),
       ...options,

packages/core/notifications/core-notifications-browser-internal/src/toasts/toasts_service.tsx

@@ -38,7 +38,7 @@ export class ToastsService {
   }
 
   public start({ i18n, overlays, theme, targetDomElement }: StartDeps) {
-    this.api!.start({ overlays, i18n });
+    this.api!.start({ overlays, i18n, theme });
     this.targetDomElement = targetDomElement;
 
     render(