fix errcheck warnings (#1739)

gin.go

@@ -422,7 +422,10 @@ func serveError(c *Context, code int, defaultMessage []byte) {
 	}
 	if c.writermem.Status() == code {
 		c.writermem.Header()["Content-Type"] = mimePlain
-		c.Writer.Write(defaultMessage)
+		_, err := c.Writer.Write(defaultMessage)
+		if err != nil {
+			debugPrint("cannot write message to writer during serve error: %v", err)
+		}
 		return
 	}
 	c.writermem.WriteHeaderNow()