[chore] fix useless assignments to local variables

This commit addresses all the instances of useless assignments to
local variables, as found by LGTM.com

components/icon/index.tsx

@@ -138,7 +138,7 @@ const Icon: IconComponent<IconProps> = props => {
       );
     }
     computedType = withThemeSuffix(
-      removeTypeTheme(alias(type)),
+      removeTypeTheme(alias(computedType)),
       dangerousTheme || theme || defaultTheme,
     );
     innerNode = (

components/table/Table.tsx

@@ -554,10 +554,8 @@ export default class Table<T> extends React.Component<TableProps<T>, TableState<
   handleRadioSelect = (record: T, rowIndex: number, e: RadioChangeEvent) => {
     const checked = e.target.checked;
     const nativeEvent = e.nativeEvent;
-    const defaultSelection = this.store.getState().selectionDirty ? [] : this.getDefaultSelection();
-    let selectedRowKeys = this.store.getState().selectedRowKeys.concat(defaultSelection);
     const key = this.getRecordKey(record, rowIndex);
-    selectedRowKeys = [key];
+    const selectedRowKeys = [key];
     this.store.setState({
       selectionDirty: true,
     });

components/tree/DirectoryTree.tsx

@@ -143,7 +143,7 @@ export default class DirectoryTree extends React.Component<DirectoryTreeProps, D
     const shiftPick: boolean = nativeEvent.shiftKey;
 
     // Generate new selected keys
-    let newSelectedKeys = selectedKeys.slice();
+    let newSelectedKeys: string[];
     if (multiple && ctrlPick) {
       // Control click
       newSelectedKeys = keys;