fix(issue-details): Fix typescript errors in tombstones banner

Add explicit ExceptionValue type annotation for the mechanism check
callback parameter, and add fallback for CodeBlock children to satisfy
the string type constraint. Restore isError bail-out.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: romtsn

static/app/components/events/interfaces/crashContent/exception/androidNativeTombstonesBanner.tsx

@@ -8,7 +8,7 @@ import {usePrompt} from 'sentry/actionCreators/prompts';
 import {DropdownMenu} from 'sentry/components/dropdownMenu';
 import {IconClose} from 'sentry/icons';
 import {t} from 'sentry/locale';
-import type {EntryException, Event} from 'sentry/types/event';
+import type {EntryException, Event, ExceptionValue} from 'sentry/types/event';
 import {EntryType} from 'sentry/types/event';
 import {trackAnalytics} from 'sentry/utils/analytics';
 import {useOrganization} from 'sentry/utils/useOrganization';
@@ -40,7 +40,7 @@ function hasSignalHandlerMechanism(event: Event): boolean {
   }
   return (
     exceptionEntry.data.values?.some(
-      value => value.mechanism?.type === 'signalhandler'
+      (value: ExceptionValue) => value.mechanism?.type === 'signalhandler'
     ) ?? false
   );
 }
@@ -92,7 +92,7 @@ export function AndroidNativeTombstonesBanner({event, projectId}: Props) {
           onTabClick={setCodeTab}
           language={codeTab === 'manifest' ? 'xml' : codeTab}
         >
-          {CODE_SNIPPETS[codeTab]}
+          {CODE_SNIPPETS[codeTab] ?? ''}
         </CodeBlock>
         <LinkButton
           style={{marginTop: '12px'}}