fix(lint): add missing return type

src/client.ts

@@ -112,7 +112,7 @@ export class Deko {
   }
 
   /** Connects to the WebSocket server and does handshake. */
-  async connect() {
+  async connect(): Promise<void> {
     if (this.state !== DekoState.CLOSED) {
       throw new Deno.errors.ConnectionRefused(
         `The client state is: ${DekoState[this.state]}`,
@@ -158,7 +158,7 @@ export class Deko {
   }
 
   /** Sends a message frame to the websocket. */
-  sendMessage(mes: string | Uint8Array) {
+  sendMessage(mes: string | Uint8Array): Promise<void> {
     if (typeof mes === "string") {
       return this.sendFrame(OpCode.TextFrame, encode(mes));
     }
@@ -167,17 +167,17 @@ export class Deko {
   }
 
   /** Sends a ping message to the websocket. */
-  sendPing(data?: Uint8Array) {
+  sendPing(data?: Uint8Array): Promise<void> {
     return this.sendFrame(OpCode.Ping, data);
   }
 
   /** Sends a pong message to the websocket. */
-  sendPong(data?: Uint8Array) {
+  sendPong(data?: Uint8Array): Promise<void> {
     return this.sendFrame(OpCode.Pong, data);
   }
 
   /** Sends a frame to the websocket. */
-  async sendFrame(opcode: OpCode, data?: Uint8Array) {
+  async sendFrame(opcode: OpCode, data?: Uint8Array): Promise<void> {
     if (this.state !== DekoState.OPEN && this.state !== DekoState.CLOSING) {
       throw new Deno.errors.NotConnected("Client is not connected");
     }
@@ -228,7 +228,7 @@ export class Deko {
   }
 
   /** Closes the WebSocket connection. */
-  async close(options: CloseOptions = {}) {
+  async close(options: CloseOptions = {}): Promise<void> {
     if (this.state === DekoState.CLOSING || this.state === DekoState.CLOSED) {
       return;
     }