fix: throw when creating components

src/widget.tsx

@@ -593,29 +593,21 @@ export class ReactModel extends DOMWidgetModel {
         );
         module = await importShim(this.codeUrl);
         if (!module) {
-          return () => <div>error loading module</div>;
+          throw new Error(`Error loading module`);
         }
       } else {
         module = await importShim(moduleName);
         if (!module) {
-          return () => <div>no module found with name {moduleName}</div>;
+          throw new Error(`no module found with name ${moduleName}`);
         }
       }
       let component = module[type || "default"];
       if (!component) {
         if (type) {
-          return () => (
-            <div>
-              no component found in module {moduleName} (with name {type})
-            </div>
-          );
+          throw new Error(`no component ${type} found in module ${moduleName}`);
         } else {
-          return () => (
-            <div>
-              no component found in module {moduleName} (it should be exported
-              as default)
-            </div>
-          );
+          throw new Error(`
+            no component found in module ${moduleName} (it should be exported as default)`);
         }
       } else {
         if (this.compiledCode) {

tests/ui/basics_test.py

@@ -82,3 +82,34 @@ def test_update_props_after_create(solara_test, page_session: playwright.sync_ap
 
     display(b)
     page_session.locator(".test-button-updated >> text=Button").wait_for()
+
+
+def test_error_module(solara_test, page_session: playwright.sync_api.Page):
+    b = ipyreact.Widget(
+        _type="Foo",
+        _module="bar",
+        children=["should not be shown"],
+    )
+    display(b)
+    page_session.locator("text=Unable to resolve specifier").wait_for()
+
+
+def test_error_type(solara_test, page_session: playwright.sync_api.Page):
+    ipyreact.define_module(
+        "my-module",
+        """
+    import * as React from "react";
+
+    export function ClickButton({value, setValue}) {
+        return React.createElement("button", {
+            className: "counter-widget",
+            onClick: () => setValue(value + 1),
+            children: [`${value|| 0} clicks`],
+        })
+    };
+    """,
+    )
+
+    b = ipyreact.ValueWidget(_module="my-module", _type="ClickButtonMistyped")
+    display(b)
+    page_session.locator("text=no component ClickButtonMistyped found in module my-module").wait_for()