Allow setState to take a partial state

React will shallow merge the provided object into the existing state¹
which works for our usage. The type definition of setState does not
allow partial state by default. Use 'never' to configure it to expect no
fields in particular².

¹ <https://react.dev/reference/react/Component#setstate-parameters>
² <https://stackoverflow.com/a/55824499>

src/components/tree/tree.tsx

@@ -136,7 +136,7 @@ export class TreeComponent extends React.Component<TreeComponentProps, TreeCompo
         this.setUpAndRenderTreeToo(this.props, newState); /* modifies newState in place */
       }
       newState.geneSortFn = sortByGeneOrder(this.props.genomeMap);
-      this.setState(newState); /* this will trigger an unnecessary CDU :( */
+      this.setState<never>(newState); /* this will trigger an unnecessary CDU :( */
     }
   }
 
@@ -174,7 +174,7 @@ export class TreeComponent extends React.Component<TreeComponentProps, TreeCompo
     if (this.tangleRef && (leftTreeUpdated || rightTreeUpdated)) {
       this.tangleRef.drawLines();
     }
-    if (Object.keys(newState).length) this.setState(newState);
+    if (Object.keys(newState).length) this.setState<never>(newState);
   }
 
   override componentWillUnmount() {