Fix NoneType errors in _ExtractTargetSourceMaps
Fix NoneType errors in _ExtractTargetSourceMaps

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PiperOrigin-RevId: 179098833
MOS_MIGRATED_REVID=179098833

pinterest/tulsi,bazelbuild/tulsi,pinterest/tulsi,bazelbuild/tulsi,pinterest/tulsi,bazelbuild/tulsi,pinterest/tulsi,bazelbuild/tulsi,pinterest/tulsi,pinterest/tulsi,bazelbuild/tulsi,bazelbuild/tulsi