Cleaned, refactored, added db init script

internal/error.go

@@ -0,0 +1,15 @@
+package internal
+
+import (
+	"net/http"
+
+	"github.com/gin-gonic/gin"
+)
+
+type errorMessage struct {
+	Message string `json:"message"`
+}
+
+func SendErrorMessageToClient(c *gin.Context, message string) {
+	c.JSON(http.StatusBadRequest, errorMessage{Message: message})
+}