Fixes#23569
## Summary
HTML imports require bundling to work correctly, as they need to process
and transform linked assets (JS/CSS). When `--no-bundle` is used, no
bundling or transformation happens, which causes a crash.
This change adds validation to detect HTML entrypoints when
`--no-bundle` is used and provides a clear error message explaining that
"HTML imports are only supported when bundling".
## Changes
- Added validation in `src/cli/build_command.zig` to check for HTML
entrypoints when `--no-bundle` flag is used
- Shows clear error message: "HTML imports are only supported when
bundling"
- Added regression tests in `test/regression/issue/23569.test.ts`
## Test Plan
### Before
```bash
$ bun build ./index.html --no-bundle
# Crashes without helpful error
```
### After
```bash
$ bun build ./index.html --no-bundle
error: HTML imports are only supported when bundling
```
### Tests
- ✅ Test with `--no-bundle` flag errors correctly
- ✅ Test with `--no-bundle --outdir` errors correctly
- ✅ Test without `--no-bundle` works normally
- ✅ All 3 regression tests pass
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Co-Authored-By: Claude <noreply@anthropic.com>
---------
Co-authored-by: Claude Bot <claude-bot@bun.sh>
Co-authored-by: Claude <noreply@anthropic.com>
