feat(errors): add snowpack env var support for assert

packages/errors/src/assert.ts

@@ -1,5 +1,10 @@
 import { defError } from "./deferror";
 
+// FIXME https://github.com/snowpackjs/snowpack/issues/3621#issuecomment-907731004
+import.meta.hot;
+
+declare const __SNOWPACK_ENV__: any;
+
 export const AssertionError = defError<any>(() => "Assertion failed");
 
 /**
@@ -10,15 +15,15 @@ export const AssertionError = defError<any>(() => "Assertion failed");
  * The function is only enabled if `process.env.NODE_ENV != "production"`
  * or if the `UMBRELLA_ASSERTS` env var is set to 1.
  */
-export const assert = (() => {
-    try {
-        return (
-            process.env.NODE_ENV !== "production" ||
-            process.env.UMBRELLA_ASSERTS === "1"
-        );
-    } catch (e) {}
-    return false;
-})()
+export const assert = (() =>
+    typeof process !== "undefined" && typeof process.env !== "undefined"
+        ? process.env.NODE_ENV !== "production" ||
+          !!process.env.UMBRELLA_ASSERTS
+        : typeof __SNOWPACK_ENV__ !== "undefined"
+        ? __SNOWPACK_ENV__.MODE !== "production" ||
+          !!__SNOWPACK_ENV__.UMBRELLA_ASSERTS ||
+          !!__SNOWPACK_ENV__.SNOWPACK_PUBLIC_UMBRELLA_ASSERTS
+        : true)()
     ? (test: boolean | (() => boolean), msg?: string | (() => string)) => {
           if ((typeof test === "function" && !test()) || !test) {
               throw new AssertionError(typeof msg === "function" ? msg() : msg);