diff --git a/js/api.js b/js/api.js
index 39d57c86c..629a2523f 100644
--- a/js/api.js
+++ b/js/api.js
@@ -85,31 +85,27 @@ window.textsecure.api = function() {
 									}
 									if (code > 999 || code < 100)
 										code = -1;
-									var e = new Error(code);
-									e.name = "HTTPError";
-									switch (code) {
-									case -1:
-										e.human_error = "Failed to connect to the server, please check your network connection.";
-										break;
-									case 413:
-										e.human_error = "Rate limit exceeded, please try again later.";
-										break;
-									case 403:
-										e.human_error = "Invalid code, please try again.";
-										break;
-									case 417:
-										e.human_error = "Number already registered"; // TODO: This shouldn't be a thing?, but its in the API doc?
-										break;
-									case 401:
-										e.human_error = "Invalid authentication, most likely someone re-registered and invalidated our registration";
-										break;
-									case 404:
-										e.human_error = "Number is not registered with TextSecure..";
-										break;
-									default:
-										e.human_error = "The server rejected our query, please file a bug report.";
+									try {
+										switch (code) {
+										case -1:
+											textsecure.throwHumanError(code, "HTTPError", "Failed to connect to the server, please check your network connection.");
+										case 413:
+											textsecure.throwHumanError(code, "HTTPError", "Rate limit exceeded, please try again later.");
+										case 403:
+											textsecure.throwHumanError(code, "HTTPError", "Invalid code, please try again.");
+										case 417:
+											// TODO: This shouldn't be a thing?, but its in the API doc?
+											textsecure.throwHumanError(code, "HTTPError", "Number already registered.");
+										case 401:
+											textsecure.throwHumanError(code, "HTTPError", "Invalid authentication, most likely someone re-registered and invalidated our registration.");
+										case 404:
+											textsecure.throwHumanError(code, "HTTPError", "Number is not registered with TextSecure.");
+										default:
+											textsecure.throwHumanError(code, "HTTPError", "The server rejected our query, please file a bug report.");
+										}
+									} catch (e) {
+										reject(e);
 									}
-									reject(e);
 								}
 			});
 		});
diff --git a/js/crypto.js b/js/crypto.js
index c6aaeccc4..d2b7777dd 100644
--- a/js/crypto.js
+++ b/js/crypto.js
@@ -417,10 +417,7 @@ window.textsecure.crypto = new function() {
 			} else {
 				// ...otherwise create an error that the UI will pick up and ask the user if they want to re-negotiate
 				// TODO: Save the message for possible later renegotiation
-				var error = new Error("Received message with unknown identity key");
-				error.name = "WarnTryAgainError";
-				error.full_message = "The identity of the sender has changed. This may be malicious, or the sender may have simply reinstalled TextSecure.";
-				throw new error;
+				textsecure.throwHumanError("Received message with unknown identity key", "WarnTryAgainError", "The identity of the sender has changed. This may be malicious, or the sender may have simply reinstalled TextSecure.");
 			}
 		}
 		return initSession(false, preKeyPair, encodedNumber, toArrayBuffer(message.identityKey), toArrayBuffer(message.baseKey))
diff --git a/js/helpers.js b/js/helpers.js
index 45107990b..9c56ad34e 100644
--- a/js/helpers.js
+++ b/js/helpers.js
@@ -277,6 +277,14 @@ window.textsecure.utils = function() {
 	return self;
 }();
 
+window.textsecure.throwHumanError = function(error, type, humanError) {
+	var e = new Error(error);
+	if (type !== undefined)
+		e.name = type;
+	e.humanError = humanError;
+	throw e;
+}
+
 /************************************************
  *** Utilities to store data in local storage ***
  ************************************************/
@@ -500,6 +508,7 @@ window.textsecure.subscribeToPush = function() {
 						});
 					})
 				}).catch(function(e) {
+					// TODO: Show "Invalid message" messages?
 					console.log("Error handling incoming message: ");
 					console.log(e);
 				});
@@ -533,20 +542,11 @@ window.textsecure.sendMessage = function() {
 		var promises = [];
 
 		var addEncryptionFor = function(i) {
-			return textsecure.crypto.encryptMessageFor(deviceObjectList[i], message).then(function(encryptedMsg) {
-				jsonData[i] = {
-					type: encryptedMsg.type,
-					destination: deviceObjectList[i].encodedNumber,
-					destinationRegistrationId: deviceObjectList[i].registrationId,
-					body: encryptedMsg.body,
-					timestamp: new Date().getTime()
-				};
-
+			return new Promise(function(resolve) { // Wrap in a promise for the throws
 				if (deviceObjectList[i].relay !== undefined) {
-					jsonData[i].relay = deviceObjectList[i].relay;
 					if (relay === undefined)
-						relay = jsonData[i].relay;
-					else if (relay != jsonData[i].relay)
+						relay = deviceObjectList[i].relay;
+					else if (relay != deviceObjectList[i].relay)
 						throw new Error("Mismatched relays for number " + number);
 				} else {
 					if (relay === undefined)
@@ -554,8 +554,22 @@ window.textsecure.sendMessage = function() {
 					else if (relay != "")
 						throw new Error("Mismatched relays for number " + number);
 				}
+
+				return textsecure.crypto.encryptMessageFor(deviceObjectList[i], message).then(function(encryptedMsg) {
+					jsonData[i] = {
+						type: encryptedMsg.type,
+						destination: deviceObjectList[i].encodedNumber,
+						destinationRegistrationId: deviceObjectList[i].registrationId,
+						body: encryptedMsg.body,
+						timestamp: new Date().getTime()
+					};
+
+					if (deviceObjectList[i].relay !== undefined)
+						jsonData[i].relay = deviceObjectList[i].relay;
+				});
 			});
 		}
+
 		for (var i = 0; i < deviceObjectList.length; i++)
 			promises[i] = addEncryptionFor(i);
 		return Promise.all(promises).then(function() {
@@ -575,6 +589,8 @@ window.textsecure.sendMessage = function() {
 		}
 
 		var registerError = function(number, message, error) {
+			if (error.humanError)
+				message = error.humanError;
 			errors[errors.length] = { number: number, reason: message, error: error };
 			numberCompleted();
 		}
diff --git a/js/options.js b/js/options.js
index e0082f985..562b413de 100644
--- a/js/options.js
+++ b/js/options.js
@@ -100,7 +100,11 @@ $('#init-go').click(function() {
 			registrationDone();
 		}
 	}).catch(function(error) {
-		alert(error.human_error);
+		//TODO: No alerts...
+		if (error.humanError)
+			alert(error.humanError);
+		else
+			alert(error); //XXX
 	});
 });
 
diff --git a/js/webcrypto.js b/js/webcrypto.js
index 1394ea7dc..2092f47f1 100644
--- a/js/webcrypto.js
+++ b/js/webcrypto.js
@@ -23,7 +23,7 @@ window.crypto.subtle = (function() {
 		var StaticArrayBufferProto = new ArrayBuffer().__proto__;
 		function assertIsArrayBuffer(thing) {
 			if (thing !== Object(thing) || thing.__proto__ != StaticArrayBufferProto)
-				throw new Error("WARNING: Needed a ArrayBuffer");
+				throw new Error("Needed a ArrayBuffer");
 		}
 
 		// private implementation functions