Implement native SimpleRenderer reference pipeline (#76)

crates/libremetaverse-types/src/shim.rs

@@ -68,6 +68,13 @@ pub enum Error {
     HttpRequest,
     /// A host lookup or socket operation failed.
     Socket,
+    /// Rendering failed while processing one source object at a named stage.
+    Rendering {
+        /// UUID of the primitive whose geometry could not be produced.
+        source: crate::UUID,
+        /// Stable stage suitable for diagnostics and fixture assertions.
+        context: &'static str,
+    },
 }
 
 impl Error {
@@ -83,7 +90,8 @@ impl Error {
             | Self::Parse { .. }
             | Self::Cancelled
             | Self::HttpRequest
-            | Self::Socket => None,
+            | Self::Socket
+            | Self::Rendering { .. } => None,
         }
     }
 }
@@ -110,6 +118,9 @@ impl fmt::Display for Error {
             Self::Cancelled => formatter.write_str("operation was cancelled"),
             Self::HttpRequest => formatter.write_str("HTTP request failed"),
             Self::Socket => formatter.write_str("socket operation failed"),
+            Self::Rendering { source, context } => {
+                write!(formatter, "rendering object {source} failed: {context}")
+            }
         }
     }
 }