diff --git a/src/api/client.ts b/src/api/client.ts
index d1b3185..1eb638b 100644
--- a/src/api/client.ts
+++ b/src/api/client.ts
@@ -128,21 +128,22 @@ export default async function execute<T>(
                 ? INVALID_TOKEN_MSG(environment)
                 : MISSING_TOKEN_MSG(environment);
 
-            // Get the user's action.
-            const selectedButton = await window.showErrorMessage(
+            // Get the user's action. We cannot use async/await here since this
+            // will block processing.
+            window.showErrorMessage(
                 `${msg} To correctly set up your token in Visual Studio Code, click the Instructions button below.`,
                 VIEW_INSTRUCTIONS_ACTION,
                 OPEN_SETTINGS_ACTION,
-            );
-
-            // Handle the action.
-            if (selectedButton === VIEW_INSTRUCTIONS_ACTION) {
-                // Open the instructions in the user's web browser.
-                env.openExternal(TOKEN_INSTUCTIONS_URL);
-            } else if (selectedButton === OPEN_SETTINGS_ACTION) {
-                // Open the token settings.
-                commands.executeCommand("dodona.settings.token");
-            }
+            ).then(action => {
+                // Handle the action.
+                if (action === VIEW_INSTRUCTIONS_ACTION) {
+                    // Open the instructions in the user's web browser.
+                    env.openExternal(TOKEN_INSTUCTIONS_URL);
+                } else if (action === OPEN_SETTINGS_ACTION) {
+                    // Open the token settings.
+                    commands.executeCommand("dodona.settings.token");
+                }
+            });
         }
 
         // Empty response.
diff --git a/src/extension.ts b/src/extension.ts
index f193d58..4ed82e1 100644
--- a/src/extension.ts
+++ b/src/extension.ts
@@ -1,7 +1,7 @@
 import { commands, ExtensionContext, window, workspace } from "vscode";
 import RootDataProvider from "./treeView/dataProvider";
 import { createNewExercise } from "./commands/createNewExercise";
-import { getApiEnvironment } from "./configuration";
+import { CONFIG_KEY, getApiEnvironment } from "./configuration";
 import { openCourse } from "./commands/openCourse";
 import { openSeries } from "./commands/openSeries";
 import { submitSolution } from "./commands/submitSolution";
@@ -99,11 +99,12 @@ export function activate(context: ExtensionContext) {
 
     // Register and create the activity tree view for the plugin.
     window.registerTreeDataProvider("dodona-activities", treeDataProvider);
-    window.createTreeView("dodona-activities", { treeDataProvider });
 
     // Refresh the treeview when the API domain is changed.
-    workspace.onDidChangeConfiguration(() => {
-        treeDataProvider.refresh();
+    workspace.onDidChangeConfiguration(e => {
+        if (e.affectsConfiguration(CONFIG_KEY)) {
+            treeDataProvider.refresh();
+        }
     });
 
     notificationsInterval();
diff --git a/src/treeView/dataProvider.ts b/src/treeView/dataProvider.ts
index 450272f..2d0ea63 100644
--- a/src/treeView/dataProvider.ts
+++ b/src/treeView/dataProvider.ts
@@ -9,9 +9,9 @@ import { AbstractTreeItem } from "./items/abstractTreeItem";
 import execute from "../api/client";
 import { YearTreeItem } from "./items/yearTreeItem";
 import {
+    getCourseFilter,
     getSortOption,
     getYearFilter,
-    getCourseFilter,
 } from "../configuration";
 import { Course } from "../api/resources/course";
 
@@ -23,9 +23,7 @@ import { Course } from "../api/resources/course";
 
 export default class RootDataProvider
     implements TreeDataProvider<AbstractTreeItem> {
-    private _onDidChangeTreeData: EventEmitter<
-        AbstractTreeItem | undefined
-    > = new EventEmitter<AbstractTreeItem | undefined>();
+    private _onDidChangeTreeData: EventEmitter<AbstractTreeItem | undefined> = new EventEmitter<AbstractTreeItem | undefined>();
     readonly onDidChangeTreeData: Event<AbstractTreeItem | undefined> = this
         ._onDidChangeTreeData.event;
 
@@ -38,19 +36,19 @@ export default class RootDataProvider
         }
 
         // Get the courses the user is subscribed to.
-        return (
-            execute(dodona => dodona.courses.subscribed)
-                // Sort courses & apply filters
-                .then(cs =>
-                    RootDataProvider.sortCourses(this.filterCourses(cs || [])),
-                )
-                // Convert them to tree items.
-                .then(cs =>
-                    this.getYears(cs).map(
-                        y => new YearTreeItem(y, this.getCoursesForYear(y, cs)),
-                    ),
-                )
-        );
+        return execute(dodona => dodona.courses.subscribed)
+            // Sort courses & apply filters
+            .then(cs =>
+                RootDataProvider.sortCourses(this.filterCourses(cs || [])),
+            )
+            // Convert them to tree items.
+            .then(cs =>
+                this.getYears(cs).map(
+                    y => new YearTreeItem(y, this.getCoursesForYear(y, cs)),
+                ),
+            )
+            // Error handling.
+            .catch(() => []);
     }
 
     /**
@@ -90,12 +88,12 @@ export default class RootDataProvider
             a.year < b.year
                 ? 1
                 : a.year > b.year
-                ? -1
-                : a.name < b.name
-                ? priority
-                : a.name > b.name
-                ? -priority
-                : 0,
+                    ? -1
+                    : a.name < b.name
+                        ? priority
+                        : a.name > b.name
+                            ? -priority
+                            : 0,
         );
     }