fix: throw better errors for users who are missing 'fetch' (#132)

src/plugin.js

@@ -16,6 +16,7 @@ import { postprocess } from '#postprocess';
 // TODO: improve generic type passed here
 /** @type {import('@unocss/core').Preset<object>} */
 export function presetWarp (options = {}) {
+  checkEnvironment();
   const externalizeClasses = options.externalizeClasses;
   const externalClasses = options.externalClasses ?? []; // will possibly be our own list in the future
   const theme = useTheme(options);
@@ -30,4 +31,14 @@ export function presetWarp (options = {}) {
   };
 }
 
+function checkEnvironment() {
+  if (typeof fetch === 'undefined') {
+    if (typeof process !== 'undefined') {
+      const NODE_MAJOR_VERSION = process.versions.node.split('.')[0];
+      if (NODE_MAJOR_VERSION < 18) throw new Error('Warp requires node 18 or higher');
+    }
+    throw new Error("'fetch' is undefined for some reason and presetWarp requires it");
+  }
+}
+
 export default presetWarp;