Reapply "use event.message when no event.error in HMR during event" (#25360)

This reverts commit b4c8379447.

### What does this PR do?

### How did you verify your code works?

---------

Co-authored-by: Claude Bot <claude-bot@bun.sh>
Co-authored-by: Claude <noreply@anthropic.com>

packages/bun-error/index.tsx

@@ -615,7 +615,6 @@ const NativeStackFrame = ({
       <div
         title={StackFrameScope[scope]}
         className="BunError-StackFrame-identifier"
-        // @ts-expect-error Custom CSS variables are not known by TypeScript
         style={{ "--max-length": `${maxLength}ch` }}
       >
         {getNativeStackFrameIdentifier(frame)}