fix: prevent undefined values in TextNodeRenderable components

[MatGros]

Summary

• Fix fatal crash: TextNodeRenderable only accepts strings, TextNodeRenderable instances, or StyledText instances

Changes

• Line 1817 (Patch component): Remove optional chaining ?. on props.output since the <Match when={props.output !== undefined}> guard already ensures it's defined. Use non-null assertion ! instead.
• Line 1232 (error message display): Add nullish coalescing ?? "" for error.data?.message to provide empty string fallback when data is undefined.

Root Cause

The <text> component from @opentui/core only accepts strings, TextNodeRenderable instances, or StyledText instances. Optional chaining (?.) can return undefined even inside guarded blocks, causing the runtime error.

Testing

The fix ensures all <text> children are guaranteed to be strings:

• props.output!.trim() - Safe because Match guard checks props.output !== undefined
• props.message.error?.data?.message ?? "" - Falls back to empty string