Prevent unused imports for engine debug output

In the process, switch from the `web-sys` crate's `console::log_1`
function to Sycamore's more flexible `console_log` macro. The latter
works both inside and outside the browser, so we can use it without
checking whether we're compiling to WebAssembly.

app-proto/src/components/add_remove.rs

@@ -18,6 +18,16 @@ pub fn AddRemove() -> View {
                         // this call is batched to avoid redundant realizations.
                         // it updates the element list and the regulator list,
                         // which are both tracked by the realization effect
+                        /* TO DO */
+                        // it would make more to do the batching inside
+                        // `insert_element_default`, but that will have to wait
+                        // until Sycamore handles nested batches correctly.
+                        //
+                        //   https://github.com/sycamore-rs/sycamore/issues/802
+                        //
+                        // the nested batch issue is relevant here because the
+                        // assembly loaders in the test assembly chooser use
+                        // `insert_element_default` within larger batches
                         state.assembly.insert_element_default::<Sphere>();
                     });
                 }

app-proto/src/engine.rs

@@ -1,7 +1,10 @@
 use lazy_static::lazy_static;
 use nalgebra::{Const, DMatrix, DVector, DVectorView, Dyn, SymmetricEigen};
 use std::fmt::{Display, Error, Formatter};
-use web_sys::{console, wasm_bindgen::JsValue}; /* DEBUG */
+
+/* DEBUG */
+#[cfg(not(feature = "dev"))]
+use sycamore::prelude::console_log;
 
 // --- elements ---
 
@@ -167,10 +170,8 @@ impl ConfigSubspace {
         
         /* DEBUG */
         // print the eigenvalues
-        #[cfg(all(target_family = "wasm", target_os = "unknown"))]
+        #[cfg(not(feature = "dev"))]
-        console::log_1(&JsValue::from(
+        console_log!("Eigenvalues used to find kernel:{}", eig.eigenvalues);
-            format!("Eigenvalues used to find kernel:{}", eig.eigenvalues)
-        ));
         
         // express the basis in the standard coordinates
         let basis_std = proj_to_std * &basis_proj;