handle requestAdapter returning null better

I'm not sure this is better? The old way printed errors
about trying to look at properties of null. The new way
says "WebGPU looks disabled". This means `navigator.gpu` exists
but `requestAdapter` returned null for all cases

index.js

@@ -1,4 +1,3 @@
-
 function makeTable(members, defaults, table) {
   const result = {};
   for (const [k, v] of Object.entries(table)) {
@@ -456,8 +455,8 @@ async function checkWorkers() {
 
 function adapterOptionsToDesc(requestAdapterOptions, adapter) {
   const parts = [
-    ...(adapter.isFallbackAdapter ? ['fallback'] : []),
-    ...(adapter.isCompatibilityMode ? ['compatibilityMode'] : []),
+    ...(adapter?.isFallbackAdapter ? ['fallback'] : []),
+    ...(adapter?.isCompatibilityMode ? ['compatibilityMode'] : []),
   ];
   return parts.length > 0
     ? parts.join(' ')