fix: avoid runtime error by ignoring keyless keyup events (#417)

.changeset/polite-seas-rule.md

@@ -0,0 +1,5 @@
+---
+'@sveltejs/vite-plugin-svelte': patch
+---
+
+ignore keyup events without key in inspector

packages/vite-plugin-svelte/src/ui/inspector/Inspector.svelte

@@ -99,7 +99,7 @@
 	}
 
 	function keydown(event) {
-		if (event.repeat || event.key === undefined) {
+		if (event.repeat || event.key == null) {
 			return;
 		}
 
@@ -112,7 +112,7 @@
 	}
 
 	function keyup(event) {
-		if (event.repeat) {
+		if (event.repeat || event.key == null) {
 			return;
 		}
 		const k = event.key.toLowerCase();