src/vs/workbench/common/editor.ts/isResourceDiffEditorInput
export function isResourceDiffEditorInput(editor: unknown): editor is IResourceDiffEditorInput {
	if (isEditorInput(editor)) {
		return false; // make sure to not accidentally match on typed editor inputs
	}

	const candidate = editor as IResourceDiffEditorInput | undefined;

	return candidate?.original !== undefined && candidate.modified !== undefined;
}