Remove assertion, use ! instead

Author: DuncanUszkay1

src/program.ts

@@ -1044,9 +1044,7 @@ export class Program extends DiagnosticEmitter {
       // TODO: for (let [alias, name] of globalAliases) {
       for (let _keys = Map_keys(globalAliases), i = 0, k = _keys.length; i < k; ++i) {
         let alias = unchecked(_keys[i]);
-        let name = globalAliases.get(alias);
-        assert(isString(name));
-        name = name!
+        let name = changetype<string>(globalAliases.get(alias))!
         if (!name.length) continue; // explicitly disabled
         let firstChar = name.charCodeAt(0);
         if (firstChar >= CharCode._0 && firstChar <= CharCode._9) {