diff --git a/dom/crypto/test/test_WebCrypto.html b/dom/crypto/test/test_WebCrypto.html
index d68f15d340507..2892b217ea528 100644
--- a/dom/crypto/test/test_WebCrypto.html
+++ b/dom/crypto/test/test_WebCrypto.html
@@ -491,8 +491,7 @@
 
     function doEncrypt(x) {
       return encrypt(x, new Uint8Array(15))
-        .catch(function () { return encrypt(new Uint8Array(17)); }
-        );
+        .catch(function () { return encrypt(new Uint8Array(17)); });
     }
 
     crypto.subtle.importKey("raw", tv.aes_cbc_enc.key, "AES-CBC", false, ['encrypt'])
@@ -539,8 +538,7 @@
 
     function doDecrypt(x) {
       return decrypt(x, new Uint8Array(15))
-        .catch(function () { return decrypt(x, new Uint8Array(17)); }
-        );
+        .catch(function () { return decrypt(x, new Uint8Array(17)); });
     }
 
     crypto.subtle.importKey("raw", tv.aes_cbc_dec.key, "AES-CBC", false, ['decrypt'])
@@ -587,8 +585,7 @@
 
     function doEncrypt(x) {
       return encrypt(x, new Uint8Array(15))
-        .catch(function () { return encrypt(x, new Uint8Array(17)); }
-        );
+        .catch(function () { return encrypt(x, new Uint8Array(17)); });
     }
 
     crypto.subtle.importKey("raw", tv.aes_ctr_enc.key, "AES-CTR", false, ['encrypt'])
@@ -635,8 +632,7 @@
 
     function decrypt(x) {
       return decrypt(x, new Uint8Array(15))
-        .catch(function () { return decrypt(x, new Uint8Array(17)); }
-        );
+        .catch(function () { return decrypt(x, new Uint8Array(17)); });
     }
 
     crypto.subtle.importKey("raw", tv.aes_ctr_dec.key, "AES-CTR", false, ['decrypt'])
diff --git a/dom/promise/tests/unit/test_monitor_uncaught.js b/dom/promise/tests/unit/test_monitor_uncaught.js
index 253a3750c1b11..8afc485931c2e 100644
--- a/dom/promise/tests/unit/test_monitor_uncaught.js
+++ b/dom/promise/tests/unit/test_monitor_uncaught.js
@@ -103,7 +103,7 @@ add_task(function* test_observe_uncaught() {
     };
     yield {
       promise: Promise.resolve(0).catch(null),
-      name: "`then(null, null)`"
+      name: "`catch(null)`"
     };
     yield {
       promise: Promise.reject(0).catch(() => {}),
diff --git a/services/fxaccounts/tests/xpcshell/test_oauth_grant_client.js b/services/fxaccounts/tests/xpcshell/test_oauth_grant_client.js
index d03e4f62290aa..41158318529b8 100644
--- a/services/fxaccounts/tests/xpcshell/test_oauth_grant_client.js
+++ b/services/fxaccounts/tests/xpcshell/test_oauth_grant_client.js
@@ -106,14 +106,13 @@ add_test(function parseErrorResponse() {
   client._Request = new mockResponse(response);
   client.getTokenFromAssertion("assertion", "scope")
     .catch(function(e) {
-        do_check_eq(e.name, "FxAccountsOAuthGrantClientError");
-        do_check_eq(e.code, STATUS_SUCCESS);
-        do_check_eq(e.errno, ERRNO_PARSE);
-        do_check_eq(e.error, ERROR_PARSE);
-        do_check_eq(e.message, "unexpected");
-        run_next_test();
-      }
-    );
+      do_check_eq(e.name, "FxAccountsOAuthGrantClientError");
+      do_check_eq(e.code, STATUS_SUCCESS);
+      do_check_eq(e.errno, ERRNO_PARSE);
+      do_check_eq(e.error, ERROR_PARSE);
+      do_check_eq(e.message, "unexpected");
+      run_next_test();
+    });
 });
 
 add_test(function serverErrorResponse() {
@@ -132,8 +131,7 @@ add_test(function serverErrorResponse() {
       do_check_eq(e.error, "Bad Request");
       do_check_eq(e.message, "Unauthorized");
       run_next_test();
-    }
-  );
+    });
 });
 
 add_test(function networkErrorResponse() {
@@ -144,13 +142,12 @@ add_test(function networkErrorResponse() {
   Services.prefs.setBoolPref("identity.fxaccounts.skipDeviceRegistration", true);
   client.getTokenFromAssertion("assertion", "scope")
     .catch(function(e) {
-        do_check_eq(e.name, "FxAccountsOAuthGrantClientError");
-        do_check_eq(e.code, null);
-        do_check_eq(e.errno, ERRNO_NETWORK);
-        do_check_eq(e.error, ERROR_NETWORK);
-        run_next_test();
-      }
-    ).catch(() => {}).then(() =>
+      do_check_eq(e.name, "FxAccountsOAuthGrantClientError");
+      do_check_eq(e.code, null);
+      do_check_eq(e.errno, ERRNO_NETWORK);
+      do_check_eq(e.error, ERROR_NETWORK);
+      run_next_test();
+    }).catch(() => {}).then(() =>
       Services.prefs.clearUserPref("identity.fxaccounts.skipDeviceRegistration"));
 });
 
@@ -159,14 +156,13 @@ add_test(function unsupportedMethod() {
 
   return client._createRequest("/", "PUT")
     .catch(function(e) {
-        do_check_eq(e.name, "FxAccountsOAuthGrantClientError");
-        do_check_eq(e.code, ERROR_CODE_METHOD_NOT_ALLOWED);
-        do_check_eq(e.errno, ERRNO_NETWORK);
-        do_check_eq(e.error, ERROR_NETWORK);
-        do_check_eq(e.message, ERROR_MSG_METHOD_NOT_ALLOWED);
-        run_next_test();
-      }
-    );
+      do_check_eq(e.name, "FxAccountsOAuthGrantClientError");
+      do_check_eq(e.code, ERROR_CODE_METHOD_NOT_ALLOWED);
+      do_check_eq(e.errno, ERRNO_NETWORK);
+      do_check_eq(e.error, ERROR_NETWORK);
+      do_check_eq(e.message, ERROR_MSG_METHOD_NOT_ALLOWED);
+      run_next_test();
+    });
 });
 
 add_test(function onCompleteRequestError() {
@@ -174,14 +170,13 @@ add_test(function onCompleteRequestError() {
   client._Request = new mockResponseError(new Error("onComplete error"));
   client.getTokenFromAssertion("assertion", "scope")
     .catch(function(e) {
-        do_check_eq(e.name, "FxAccountsOAuthGrantClientError");
-        do_check_eq(e.code, null);
-        do_check_eq(e.errno, ERRNO_NETWORK);
-        do_check_eq(e.error, ERROR_NETWORK);
-        do_check_eq(e.message, "Error: onComplete error");
-        run_next_test();
-      }
-  );
+      do_check_eq(e.name, "FxAccountsOAuthGrantClientError");
+      do_check_eq(e.code, null);
+      do_check_eq(e.errno, ERRNO_NETWORK);
+      do_check_eq(e.error, ERROR_NETWORK);
+      do_check_eq(e.message, "Error: onComplete error");
+      run_next_test();
+    });
 });
 
 add_test(function incorrectErrno() {
@@ -200,8 +195,7 @@ add_test(function incorrectErrno() {
       do_check_eq(e.error, "Bad Request");
       do_check_eq(e.message, "Unauthorized");
       run_next_test();
-    }
-  );
+    });
 });
 
 add_test(function constructorTests() {
diff --git a/toolkit/components/osfile/modules/osfile_async_front.jsm b/toolkit/components/osfile/modules/osfile_async_front.jsm
index adf20b728986d..a75383e83151c 100644
--- a/toolkit/components/osfile/modules/osfile_async_front.jsm
+++ b/toolkit/components/osfile/modules/osfile_async_front.jsm
@@ -376,7 +376,7 @@ var Scheduler = this.Scheduler = {
     // By definition, |this.queue| can never reject.
     this.queue = promise.catch(() => undefined);
     // Fork |promise| to ensure that uncaught errors are reported
-    return promise.catch(null);
+    return promise.then();
   },
 
   /**
diff --git a/toolkit/components/places/PlacesUtils.jsm b/toolkit/components/places/PlacesUtils.jsm
index dd8c4e6f56068..dff0e68f20f91 100644
--- a/toolkit/components/places/PlacesUtils.jsm
+++ b/toolkit/components/places/PlacesUtils.jsm
@@ -3069,7 +3069,7 @@ PlacesCreateLivemarkTransaction.prototype = {
     // The getLivemark callback may fail, but it is used just to serialize,
     // so it doesn't matter.
     this._promise = PlacesUtils.livemarks.getLivemark({ id: this.item.id })
-      .catch(null).then( () => {
+      .catch(() => {}).then(() => {
         PlacesUtils.bookmarks.removeItem(this.item.id);
       });
   }