Fix for rendering error with DOIs with null nameIdentifier

[codycooperross]

Purpose

Fix for rendering error with DOIs with null nameIdentifier.

closes: #862

Approach

Open Questions and Pre-Merge TODOs

Learning

Types of changes

• Bug fix (non-breaking change which fixes an issue)

• New feature (non-breaking change which adds functionality)

• Breaking change (fix or feature that would cause existing functionality to change)

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