Fix website building

Author: romanowski

website/src/components/basicInstall.js

@@ -2,32 +2,36 @@ import React from 'react';
 import Tabs from '@theme/Tabs';
 import TabItem from '@theme/TabItem';
 import DownloadButton from './DownloadButton';
+import BrowserOnly from '@docusaurus/BrowserOnly';
 
 const windowsPlatforms = ['Win32', 'Win64', 'Windows', 'WinCE']
 
+function defaultOS(){ return window ? (window.navigator.userAgent.indexOf("Win") != -1 ? "win" : "mac/linux") : "mac/linux" }
+
 export default function BasicInstall(props){
-  const defaultOS = window.navigator.userAgent.indexOf("Win") != -1 ? "win" : "mac/linux"
-  return <div>
-      <Tabs 
-        groupId="operating-systems"
-        defaultValue={defaultOS}
-      values={[
-        {label: 'Windows', value: 'win'},
-        {label: 'macOS/Linux', value: 'mac/linux'},
-      ]}>
-        <TabItem value="win">
-          <a className="no_monospace" href="https://github.com/Virtuslab/scala-cli/releases/download/nightly/scala-cli-x86_64-pc-win32.msi">
-            Download Scala CLI for Windows
-          </a>
-        </TabItem>
-        <TabItem value="mac/linux">
-          <p>Run the following one-line command in your terminal 
-            <br/>
-            <code> bash
-              curl -sSLf https://virtuslab.github.io/scala-cli-packages/scala-setup.sh | sh
-            </code>
-          </p>
-        </TabItem>
-      </Tabs>
-    </div>
+  return  <BrowserOnly>{() =>
+      <div>
+        <Tabs 
+          groupId="operating-systems"
+          defaultValue={defaultOS()}
+        values={[
+          {label: 'Windows', value: 'win'},
+          {label: 'macOS/Linux', value: 'mac/linux'},
+        ]}>
+          <TabItem value="win">
+            <a className="no_monospace" href="https://github.com/Virtuslab/scala-cli/releases/download/nightly/scala-cli-x86_64-pc-win32.msi">
+              Download Scala CLI for Windows
+            </a>
+          </TabItem>
+          <TabItem value="mac/linux">
+            <p>Run the following one-line command in your terminal 
+              <br/>
+              <code> bash
+                curl -sSLf https://virtuslab.github.io/scala-cli-packages/scala-setup.sh | sh
+              </code>
+            </p>
+          </TabItem>
+        </Tabs>
+      </div>          
+  }</BrowserOnly>
 }