Adapt symmetric_kernel for non-WASM targets

The examples call `engine::realize_gram`, which now includes a call to
`symmetric_kernel`, so we need to make sure that `symmetric_kernel`
can run on whatever target Cargo uses for examples. For that target on
my machine, `console::log_1` panics with the message "function not
implemented on non-`wasm32` targets".

app-proto/src/engine.rs

@@ -111,9 +111,14 @@ impl ConfigSubspace {
                 )
             )
         );
+        
+        /* DEBUG */
+        // print the eigenvalues
+        #[cfg(all(target_family = "wasm", target_os = "unknown"))]
         console::log_1(&JsValue::from(
-            format!("Hessian eigenvalues: {}", eig.eigenvalues)
+            format!("Eigenvalues used to find kernel: {}", eig.eigenvalues)
-        )); /* DEBUG */
+        ));
+        
         ConfigSubspace(basis.collect())
     }