fix NPE error when not signed in

Author: andxu

PluginsAndFeatures/azure-toolkit-for-intellij/src/com/microsoft/intellij/ui/AzurePanel.java

@@ -116,9 +116,8 @@ public void customize(@NotNull JList list, AzureEnvironment value, int index, bo
     }
 
     private void displayDescriptionForAzureEnv() {
-        final String azureEnv = AuthMethodManager.getInstance().getAuthMethodDetails().getAzureEnv();
         if (AuthMethodManager.getInstance().isSignedIn()) {
-
+            final String azureEnv = AuthMethodManager.getInstance().getAuthMethodDetails().getAzureEnv();
             final AzureEnvironment currentEnv =
                 AzureEnvironmentUtils.stringToAzureEnvironment(azureEnv);
             String currentEnvStr = azureEnvironmentToString(currentEnv);