User-friendlier errors

cli/internal/terraform/loader.go

@@ -10,7 +10,6 @@ import (
 	"bytes"
 	"embed"
 	"errors"
-	"fmt"
 	"io/fs"
 	"path"
 	"path/filepath"
@@ -21,6 +20,9 @@ import (
 	"github.com/spf13/afero"
 )
 
+// ErrTerraformWorkspaceDifferentFiles is returned when a re-used existing Terraform workspace has different files than the ones to be extracted (e.g. due to a version mix-up or incomplete writes).
+var ErrTerraformWorkspaceDifferentFiles = errors.New("creating cluster: trying to overwrite an existing Terraform file with a different version")
+
 //go:embed terraform/*
 //go:embed terraform/*/.terraform.lock.hcl
 var terraformFS embed.FS
@@ -53,7 +55,7 @@ func prepareWorkspace(fileHandler file.Handler, provider cloudprovider.Provider,
 			}
 
 			if !bytes.Equal(content, existingFileContent) {
-				return fmt.Errorf("trying to overwrite existing Terraform file with different version")
+				return ErrTerraformWorkspaceDifferentFiles
 			}
 			return nil
 		} else if err != nil {

cli/internal/terraform/terraform.go

@@ -29,6 +29,9 @@ const (
 	terraformVarsFile = "terraform.tfvars"
 )
 
+// ErrTerraformWorkspaceExistsWithDifferentVariables is returned when existing Terraform files differ from the version the CLI wants to extract.
+var ErrTerraformWorkspaceExistsWithDifferentVariables = errors.New("creating cluster: a Terraform workspace already exists with different variables")
+
 // Client manages interaction with Terraform.
 type Client struct {
 	tf tfInterface
@@ -162,7 +165,7 @@ func (c *Client) writeVars(vars Variables) error {
 			return err
 		}
 		if vars.String() != string(varsContent) {
-			return errors.New("creating cluster: workspace already exists with different variables")
+			return ErrTerraformWorkspaceExistsWithDifferentVariables
 		}
 	} else if err != nil {
 		return err