bugfix: citation component does not throw error if undefined object was passed to it

src/ui/citation/citations.template.html

-<div 
-  citationContainer
-  *ngFor = "let publication of properties.publications">
-  <a
-    target = "_blank"
-    [href] = "publication.doi"
-    *ngIf="publication.doi && publication.doi !== 'undefined'">
-    {{ publication.citation }}
-  </a> 
-  <span
-    *ngIf="(!publication.doi) || publication.doi === 'undefined'">
-    {{ publication.citation }}
-  </span>
+<div *ngIf = "properties">
+  <div 
+    citationContainer
+    *ngFor = "let publication of properties.publications">
+    <a
+      target = "_blank"
+      [href] = "publication.doi"
+      *ngIf="publication.doi && publication.doi !== 'undefined'">
+      {{ publication.citation }}
+    </a> 
+    <span
+      *ngIf="(!publication.doi) || publication.doi === 'undefined'">
+      {{ publication.citation }}
+    </span>
+  </div>
 </div>
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