test(tools): add unit tests for error handling functions

* Implement tests for error functions like errRequiredField, errInvalidField, and errEntityNotFound.
* Ensure proper metadata is returned for various error scenarios.
* Validate error handling in CRM, Files, and other tools.
* Introduce tests for parsing stored file IDs and UUIDs.
* Enhance coverage for helper functions related to project resolution and session management.

internal/app/files.go

@@ -93,7 +93,9 @@ func parseMultipartUpload(r *http.Request) (tools.SaveFileDecodedInput, error) {
 	if err != nil {
 		return tools.SaveFileDecodedInput{}, errors.New("multipart upload requires a file field named \"file\"")
 	}
-	defer file.Close()
+	defer func() {
+		_ = file.Close()
+	}()
 
 	content, err := io.ReadAll(file)
 	if err != nil {