lint: add errchecks (#5316)

## Description

Work towards enabling errcheck

ref #5059

rpc/client/rpc_test.go

@@ -190,7 +190,8 @@ func TestABCIQuery(t *testing.T) {
 		apph := bres.Height + 1 // this is where the tx will be applied to the state
 
 		// wait before querying
-		client.WaitForHeight(c, apph, nil)
+		err = client.WaitForHeight(c, apph, nil)
+		require.NoError(t, err)
 		res, err := c.ABCIQuery("/key", k)
 		qres := res.Response
 		if assert.Nil(t, err) && assert.True(t, qres.IsOK()) {
@@ -624,7 +625,8 @@ func testBatchedJSONRPCCalls(t *testing.T, c *rpchttp.HTTP) {
 	require.Equal(t, *bresult2, *r2)
 	apph := tmmath.MaxInt64(bresult1.Height, bresult2.Height) + 1
 
-	client.WaitForHeight(c, apph, nil)
+	err = client.WaitForHeight(c, apph, nil)
+	require.NoError(t, err)
 
 	q1, err := batch.ABCIQuery("/key", k1)
 	require.NoError(t, err)

rpc/jsonrpc/client/ws_client.go

@@ -349,7 +349,10 @@ func (c *WSClient) reconnectRoutine() {
 			c.wg.Wait()
 			if err := c.reconnect(); err != nil {
 				c.Logger.Error("failed to reconnect", "err", err, "original_err", originalError)
-				c.Stop()
+				if err = c.Stop(); err != nil {
+					c.Logger.Error("failed to stop conn", "error", err)
+				}
+
 				return
 			}
 			// drain reconnectAfter

rpc/jsonrpc/server/ws_handler.go

@@ -99,7 +99,9 @@ func (wm *WebsocketManager) WebsocketHandler(w http.ResponseWriter, r *http.Requ
 		wm.logger.Error("Failed to start connection", "err", err)
 		return
 	}
-	con.Stop()
+	if err := con.Stop(); err != nil {
+		wm.logger.Error("error while stopping connection", "error", err)
+	}
 }
 
 ///////////////////////////////////////////////////////////////////////////////