Changes
If Wikidata property has multiple values, only use first one; see Cathy Rigby article for example. Use whitespace with {{#if:}} to make template easier to understand and maintain. Tested with /sandbox and /testcases.
{{#if: {{{1|{{{id<includeonly>|</includeonly>}}}}}} {{#property:P1220}}
| [https://www.ibdb.com/broadway-cast-staff/{{#if: {{{1|{{{id<includeonly>|</includeonly>}}}}}}
| {{{1|{{{id}}}}}}
| {{First word|1={{#property:P1220}}|sep=,}}
}} {{#if: {{{2|{{{name<includeonly>|</includeonly>}}}}}}
| {{{2|{{{name}}}}}}
| {{PAGENAMEBASE}}
}}] at the [[Internet Broadway Database]]<includeonly>{{EditAtWikidata|pid=P1220|{{{1|{{{id|}}}}}}}}{{WikidataCheck|property=P1220|value={{{1|{{{id|}}}}}}|category=Internet Broadway Database person ID}}</includeonly>
| <span class="error">{{[[Template:IBDB name|IBDB name]]}} template missing ID and not present in Wikidata.</span>{{Main other|[[Category:IBDB name template missing ID]]}}
}}{{Main other|[[Category:Articles with IBDb links]]}}<noinclude>
{{Documentation}}
</noinclude>
| [https://www.ibdb.com/broadway-cast-staff/{{#if: {{{1|{{{id<includeonly>|</includeonly>}}}}}}
| {{{1|{{{id}}}}}}
| {{First word|1={{#property:P1220}}|sep=,}}
}} {{#if: {{{2|{{{name<includeonly>|</includeonly>}}}}}}
| {{{2|{{{name}}}}}}
| {{PAGENAMEBASE}}
}}] at the [[Internet Broadway Database]]<includeonly>{{EditAtWikidata|pid=P1220|{{{1|{{{id|}}}}}}}}{{WikidataCheck|property=P1220|value={{{1|{{{id|}}}}}}|category=Internet Broadway Database person ID}}</includeonly>
| <span class="error">{{[[Template:IBDB name|IBDB name]]}} template missing ID and not present in Wikidata.</span>{{Main other|[[Category:IBDB name template missing ID]]}}
}}{{Main other|[[Category:Articles with IBDb links]]}}<noinclude>
{{Documentation}}
</noinclude>
