Improve error message when calling project() on a symlink (#907)

Summary:
Details can be found at: #906

Improve error message when calling project() on a symlink.

Pull Request resolved: #907

Reviewed By: scottcao

Differential Revision: D73052154

fbshipit-source-id: d1096b698a99a9b60c8bc04c8f6c8a162f268594

Author: valadez-abel

Diff for: app/buck2_build_api/src/artifact_groups/calculation.rs

@@ -396,7 +396,7 @@ impl Key for EnsureProjectedArtifactKey {
 
         let value = extract_artifact_value(&builder, &base_path.join(path), digest_config)
             .with_buck_error_context(|| {
-                format!("The path `{path}` cannot be projected in the artifact `{base}`")
+                format!("The path `{path}` cannot be projected in the artifact `{base}`. Are you calling project() on a symlink?")
             })?
             .with_buck_error_context(|| {
                 format!("The path `{path}` does not exist in the artifact `{base}`")