diff --git a/services/settings/RemoteSettingsWorker.jsm b/services/settings/RemoteSettingsWorker.jsm
index 129881e1479e..3cf7b2a7f592 100644
--- a/services/settings/RemoteSettingsWorker.jsm
+++ b/services/settings/RemoteSettingsWorker.jsm
@@ -38,9 +38,7 @@ let gShutdownResolver = null;
 class Worker {
   constructor(source) {
     if (gShutdown) {
-      Cu.reportError(
-        new Error("Can't create worker once shutdown has started")
-      );
+      Cu.reportError("Can't create worker once shutdown has started");
     }
     this.source = source;
     this.worker = null;
@@ -52,7 +50,7 @@ class Worker {
 
   async _execute(method, args = []) {
     if (gShutdown) {
-      return Promise.reject(new Error("Remote Settings has shut down."));
+      throw new Error("Remote Settings has shut down.");
     }
     // (Re)instantiate the worker if it was terminated.
     if (!this.worker) {
@@ -136,7 +134,7 @@ try {
         !RemoteSettingsWorker.worker ||
         !RemoteSettingsWorker.callbacks.size
       ) {
-        return Promise.resolve();
+        return null;
       }
       // Otherwise, return a promise that the worker will resolve.
       return new Promise(resolve => {
@@ -145,9 +143,7 @@ try {
     },
     {
       fetchState() {
-        return (
-          "Remaining: " + RemoteSettingsWorker.callbacks.size + " callbacks."
-        );
+        return `Remaining: ${RemoteSettingsWorker.callbacks.size} callbacks.`;
       },
     }
   );
diff --git a/services/settings/test/unit/test_remote_settings_worker.js b/services/settings/test/unit/test_remote_settings_worker.js
index 28b20b924e19..fdd3ffa2098f 100644
--- a/services/settings/test/unit/test_remote_settings_worker.js
+++ b/services/settings/test/unit/test_remote_settings_worker.js
@@ -36,8 +36,8 @@ add_task(async function test_canonicaljson_merges_remote_into_local() {
   );
 
   Assert.equal(
-    '{"data":[{"id":"1","title":"title 1"},{"id":"2","title":"title b"}],"last_modified":"42"}',
-    serialized
+    serialized,
+    '{"data":[{"id":"1","title":"title 1"},{"id":"2","title":"title b"}],"last_modified":"42"}'
   );
 });
 
@@ -67,7 +67,7 @@ add_task(async function test_throws_error_if_worker_fails() {
   } catch (e) {
     error = e;
   }
-  Assert.equal("TypeError: localRecords is null", error.message);
+  Assert.equal(error.message, "TypeError: localRecords is null");
 });
 
 add_task(async function test_stops_worker_after_timeout() {
@@ -78,7 +78,7 @@ add_task(async function test_stops_worker_after_timeout() {
   );
   // Run a task:
   let serialized = await RemoteSettingsWorker.canonicalStringify([], [], 42);
-  Assert.equal('{"data":[],"last_modified":"42"}', serialized, "API works.");
+  Assert.equal(serialized, '{"data":[],"last_modified":"42"}', "API works.");
   // Check that the worker gets stopped now the task is done:
   await TestUtils.waitForCondition(() => !RemoteSettingsWorker.worker);
   // Ensure the worker stays alive for 10 minutes instead:
@@ -89,8 +89,8 @@ add_task(async function test_stops_worker_after_timeout() {
   // Run another task:
   serialized = await RemoteSettingsWorker.canonicalStringify([], [], 42);
   Assert.equal(
-    '{"data":[],"last_modified":"42"}',
     serialized,
+    '{"data":[],"last_modified":"42"}',
     "API still works."
   );
   Assert.ok(RemoteSettingsWorker.worker, "Worker should stay alive a bit.");