Fix panic when capture has no next sibling

[gordon-klotho]

Fixes panic:

github.com/klothoplatform/klotho/pkg/lang.(*capabilityFinder).findAllCommentsBlocks(0x1400021a0a8, 0x14000790d90)
	/Users/jordansinger/workspace/klotho/pkg/lang/capabilities.go:104 +0x244

Standard checks

• Unit tests: Any special considerations?
• Docs: Do we need to update any docs, internal or public?
• Backwards compatibility: Will this break existing apps? If so, what would be the extra work required to keep them working?

[github-actions]

Package	Line Rate	Health
github.com/klothoplatform/klotho/pkg/analytics	2%	❌
github.com/klothoplatform/klotho/pkg/annotation	23%	❌
github.com/klothoplatform/klotho/pkg/cli	4%	❌
github.com/klothoplatform/klotho/pkg/core	21%	❌
github.com/klothoplatform/klotho/pkg/env_var	82%	✔
github.com/klothoplatform/klotho/pkg/exec_unit	54%	➖
github.com/klothoplatform/klotho/pkg/infra/kubernetes	59%	➖
github.com/klothoplatform/klotho/pkg/infra/kubernetes/helm	39%	❌
github.com/klothoplatform/klotho/pkg/input	63%	➖
github.com/klothoplatform/klotho/pkg/lang	38%	❌
github.com/klothoplatform/klotho/pkg/lang/dockerfile	0%	❌
github.com/klothoplatform/klotho/pkg/lang/golang	19%	❌
github.com/klothoplatform/klotho/pkg/lang/javascript	47%	❌
github.com/klothoplatform/klotho/pkg/lang/python	60%	➖
github.com/klothoplatform/klotho/pkg/lang/yaml	0%	❌
github.com/klothoplatform/klotho/pkg/logging	7%	❌
github.com/klothoplatform/klotho/pkg/multierr	95%	✔
github.com/klothoplatform/klotho/pkg/provider/aws	59%	➖
github.com/klothoplatform/klotho/pkg/runtime	75%	✔
github.com/klothoplatform/klotho/pkg/static_unit	33%	❌
github.com/klothoplatform/klotho/pkg/validation	73%	➖
github.com/klothoplatform/klotho/pkg/yaml_util	79%	✔
Summary	40% (3793 / 9446)	❌