lib/client: encode empty SASL response as "+"

Fixes the following error when sending a message on a server
without echo-message:

    Uncaught TypeError: t.tags is undefined
        prepareChatMessage app.js:602
        handleChatMessage app.js:616
        privmsg app.js:1514
        handleComposerSubmit app.js:1535
        handleSubmit composer.js:30
        Preact 15
        handleMessage app.js:1013
        connect app.js:791
        handleMessage client.js:448
        reconnect client.js:176
        reconnect client.js:174
        Yt client.js:151
        connect app.js:754
        handleConnectSubmit app.js:1279
        handleSubmit connect-form.js:74
        Preact 16
        handleConfig app.js:382
        <anonymous> app.js:238
        promise callback* app.js:237
        Preact 4
        <anonymous> main.js:4

README.md

@@ -97,7 +97,7 @@ gamja default settings can be set using a `config.json` file at the root:
 {
 	// IRC server settings.
 	"server": {
-		// WebSocket URL or path to connect to (string).
+		// WebSocket URL or path to connect to (string). Defaults to "/socket".
 		"url": "wss://irc.example.org",
 		// Channel(s) to auto-join (string or array of strings).
 		"autojoin": "#gamja",

components/app.js

@@ -394,6 +394,7 @@ export default class App extends Component {
 		} catch (err) {
 			console.error("Failed to fetch OAuth 2.0 server metadata:", err);
 			this.showError("Failed to fetch OAuth 2.0 server metadata");
+			return;
 		}
 
 		oauth2.redirectAuthorize({
@@ -599,6 +600,10 @@ export default class App extends Component {
 			msg.isHighlight = irc.isHighlight(msg, client.nick, client.cm) || irc.isServerBroadcast(msg);
 		}
 
+		if (!msg.tags) {
+			// Can happen for outgoing messages for instance
+			msg.tags = {};
+		}
 		if (!msg.tags.time) {
 			msg.tags.time = irc.formatDate(new Date());
 		}

components/composer.js

@@ -118,8 +118,14 @@ export default class Composer extends Component {
 
 	handleWindowKeyDown(event) {
 		// If an <input> or <button> is focused, ignore.
-		if (document.activeElement !== document.body && document.activeElement.tagName !== "SECTION") {
+		if (document.activeElement && document.activeElement !== document.body) {
-			return;
+			switch (document.activeElement.tagName.toLowerCase()) {
+			case "section":
+			case "a":
+				break;
+			default:
+				return;
+			}
 		}
 
 		// If a modifier is pressed, reserve for key bindings.

lib/client.js

@@ -470,7 +470,7 @@ export default class Client extends EventTarget {
 			initialResp = { command: "AUTHENTICATE", params: [respStr] };
 			break;
 		case "EXTERNAL":
-			initialResp = { command: "AUTHENTICATE", params: [base64.encode("")] };
+			initialResp = { command: "AUTHENTICATE", params: ["+"] };
 			break;
 		case "OAUTHBEARER":
 			let raw = "n,,\x01auth=Bearer " + params.token + "\x01\x01";