feat: add initial module and main functionality

go.mod

@@ -0,0 +1,3 @@
+module go-workshop
+
+go 1.24.0

main.go

@@ -0,0 +1,10 @@
+package main
+
+import "go-workshop/test"
+
+func main() {
+	err := test.PrintString("")
+	if err != nil {
+		panic(err)
+	}
+}

test/test.go

@@ -0,0 +1,29 @@
+package test
+
+import (
+	"fmt"
+)
+
+// CustomError represents my custom error
+type CustomError struct {
+	Message string
+	Code    string
+}
+
+// Error implements error.
+func (c CustomError) Error() string {
+	return fmt.Sprintf("CustomError\nMessage: %s\nCode: %s\n", c.Message, c.Code)
+}
+
+// PrintString prints a string when not empty
+func PrintString(str string) (err error) {
+	if str == "" {
+		return CustomError{
+			Message: "Input is empty",
+			Code:    "some code",
+		}
+	}
+
+	fmt.Println(str)
+	return
+}