Gov. Chris Christie has warned potential investors there is no guarantee the state will make its required pension payments in future years, an admission that underscores a looming financial crisis he and future governors face as retirement costs are expected to explode before the decade ends. The disclosure, buried in a 156-page bond prospectus for investors, also casts doubt on one of the key commitments Christie and leading Democrats made to public employees as part of the 2011 health and pension reform: Workers would shoulder a greater share of pension costs in exchange for the state making required payments to...