fix: Fix conflicting imports type definition in loader (#1508)

Author: Martin Fredriksson

NOTICE

@@ -28,6 +28,7 @@ under the licensing terms detailed in LICENSE:
 * Maël Nison <nison.mael@gmail.com>
 * Valeria Viana Gusmao <valeria.viana.gusmao@gmail.com>
 * Gabor Greif <ggreif@gmail.com>
+* Martin Fredriksson <martin.fredriksson@vikinganalytics.se>
 
 Portions of this software are derived from third-party works licensed under
 the following terms:

lib/loader/index.d.ts

@@ -8,7 +8,7 @@ export interface ResultObject {
 
 /** WebAssembly imports with an optional env object and two levels of nesting. */
 export type Imports = {
-  [key: string]: Record<string,unknown>;
+  [key: string]: Record<string,unknown> | undefined;
   env?: {
     memory?: WebAssembly.Memory;
     table?: WebAssembly.Table;