Improve command error reporting

state.error is expected to be a String, not an Error.

commands.js

@@ -160,7 +160,7 @@ export default {
 			try {
 				msg = irc.parseMessage(args.join(" "));
 			} catch (err) {
-				throw new Error("failed to parse IRC command: " + err.message);
+				throw new Error("Failed to parse IRC command: " + err.message);
 			}
 			getActiveClient(app).send(msg);
 		},

components/app.js

@@ -945,8 +945,8 @@ export default class App extends Component {
 		try {
 			cmd.execute(this, args);
 		} catch (error) {
-			console.error("Failed to execute command '" + name + "'", error);
+			console.error("Failed to execute command '" + name + "':", error);
-			this.setState({ error });
+			this.setState({ error: error.message });
 		}
 	}