Fix some React warnings (#26609)

app/javascript/mastodon/features/explore/results.jsx

@@ -108,10 +108,10 @@ class Results extends PureComponent {
     return (
       <>
         <div className='account__section-headline'>
-          <button onClick={this.handleSelectAll} className={type === 'all' && 'active'}><FormattedMessage id='search_results.all' defaultMessage='All' /></button>
-          <button onClick={this.handleSelectAccounts} className={type === 'accounts' && 'active'}><FormattedMessage id='search_results.accounts' defaultMessage='Profiles' /></button>
-          <button onClick={this.handleSelectHashtags} className={type === 'hashtags' && 'active'}><FormattedMessage id='search_results.hashtags' defaultMessage='Hashtags' /></button>
-          <button onClick={this.handleSelectStatuses} className={type === 'statuses' && 'active'}><FormattedMessage id='search_results.statuses' defaultMessage='Posts' /></button>
+          <button onClick={this.handleSelectAll} className={type === 'all' ? 'active' : undefined}><FormattedMessage id='search_results.all' defaultMessage='All' /></button>
+          <button onClick={this.handleSelectAccounts} className={type === 'accounts' ? 'active' : undefined}><FormattedMessage id='search_results.accounts' defaultMessage='Profiles' /></button>
+          <button onClick={this.handleSelectHashtags} className={type === 'hashtags' ? 'active' : undefined}><FormattedMessage id='search_results.hashtags' defaultMessage='Hashtags' /></button>
+          <button onClick={this.handleSelectStatuses} className={type === 'statuses' ? 'active' : undefined}><FormattedMessage id='search_results.statuses' defaultMessage='Posts' /></button>
         </div>
 
         <div className='explore__search-results'>

app/javascript/mastodon/features/status/index.jsx

@@ -568,7 +568,7 @@ class Status extends ImmutablePureComponent {
         onMoveUp={this.handleMoveUp}
         onMoveDown={this.handleMoveDown}
         contextType='thread'
-        previousId={i > 0 && list.get(i - 1)}
+        previousId={i > 0 ? list.get(i - 1) : undefined}
         nextId={list.get(i + 1) || (ancestors && statusId)}
         rootId={statusId}
       />

app/javascript/mastodon/features/ui/components/modal_root.jsx

@@ -115,7 +115,10 @@ export default class ModalRoot extends PureComponent {
         {visible && (
           <>
             <BundleContainer fetchComponent={MODAL_COMPONENTS[type]} loading={this.renderLoading(type)} error={this.renderError} renderDelay={200}>
-              {(SpecificComponent) => <SpecificComponent {...props} onChangeBackgroundColor={this.setBackgroundColor} onClose={this.handleClose} ref={this.setModalRef} />}
+              {(SpecificComponent) => {
+                const ref = typeof SpecificComponent !== 'function' ? this.setModalRef : undefined;
+                return <SpecificComponent {...props} onChangeBackgroundColor={this.setBackgroundColor} onClose={this.handleClose} ref={ref} />
+              }}
             </BundleContainer>
 
             <Helmet>