Make missing IL2CPP exports throw errors only when invoked

Author: vfsfitvnm

lib/exports.ts

@@ -527,15 +527,26 @@ namespace Il2Cpp {
     getter(Il2Cpp, "memorySnapshotExports", () => new CModule($inline_file("cmodules/memory-snapshot.c")), lazy);
 
     function r<R extends NativeFunctionReturnType, A extends NativeFunctionArgumentType[] | []>(exportName: `il2cpp_${string}`, retType: R, argTypes: A) {
-        const handle = Il2Cpp.$config.exports?.[exportName]?.() ?? Il2Cpp.module.findExportByName(exportName) ?? memorySnapshotExports[exportName];
-
-        const target = new NativeFunction(handle ?? raise(`couldn't resolve export ${exportName}`), retType, argTypes);
-
-        if (target.isNull()) {
-            raise(`export ${exportName} points to NULL IL2CPP library has likely been stripped, obfuscated, or customized`);
-        }
-
-        return target;
+        const handle: NativePointer | null | undefined =
+            Il2Cpp.$config.exports?.[exportName]?.() ?? Il2Cpp.module.findExportByName(exportName) ?? memorySnapshotExports[exportName];
+
+        const target = new NativeFunction(handle ?? NULL, retType, argTypes);
+
+        return target.isNull()
+            ? new Proxy(target, {
+                  get(value: typeof target, name: keyof typeof target) {
+                      const property = value[name];
+                      return typeof property === "function" ? property.bind(value) : property;
+                  },
+                  apply() {
+                      if (handle == null) {
+                          raise(`couldn't resolve export ${exportName}`);
+                      } else if (handle.isNull()) {
+                          raise(`export ${exportName} points to NULL IL2CPP library has likely been stripped, obfuscated, or customized`);
+                      }
+                  }
+              })
+            : target;
     }
 
     declare const $inline_file: typeof import("ts-transformer-inline-file").$INLINE_FILE;

lib/structs/assembly.ts

@@ -3,37 +3,27 @@ namespace Il2Cpp {
     export class Assembly extends NativeStruct {
         /** Gets the image of this assembly. */
         get image(): Il2Cpp.Image {
-            let get = function (this: Il2Cpp.Assembly) {
-                return new Il2Cpp.Image(Il2Cpp.exports.assemblyGetImage(this));
-            };
-
-            try {
-                Il2Cpp.exports.assemblyGetImage;
-            } catch (_) {
-                get = function (this: Il2Cpp.Assembly) {
-                    // We need to get the System.Reflection.Module of the current assembly;
-                    // System.Reflection.Assembly::GetModulesInternal, for some reason,
-                    // throws a NullReferenceExceptionin Unity 5.3.8f1, so we must rely on
-                    // System.Type::get_Module instead.
-                    // Now we need to get any System.Type of this assembly.
-                    // We cannot use System.Reflection.Assembly::GetTypes because it may
-                    // return an empty array; hence we use System.Reflection.Assembly::GetType
-                    // to retrieve <Module>, a class/type that seems to be always present
-                    // (despite being excluded from System.Reflection.Assembly::GetTypes).
-                    return new Il2Cpp.Image(
-                        this.object
-                            .method<Il2Cpp.Object>("GetType", 1)
-                            .invoke(Il2Cpp.string("<Module>"))
-                            .method<Il2Cpp.Object>("get_Module")
-                            .invoke()
-                            .field<NativePointer>("_impl").value
-                    );
-                };
+            if (Il2Cpp.exports.assemblyGetImage.isNull()) {
+                // We need to get the System.Reflection.Module of the current assembly;
+                // System.Reflection.Assembly::GetModulesInternal, for some reason,
+                // throws a NullReferenceExceptionin Unity 5.3.8f1, so we must rely on
+                // System.Type::get_Module instead.
+                // Now we need to get any System.Type of this assembly.
+                // We cannot use System.Reflection.Assembly::GetTypes because it may
+                // return an empty array; hence we use System.Reflection.Assembly::GetType
+                // to retrieve <Module>, a class/type that seems to be always present
+                // (despite being excluded from System.Reflection.Assembly::GetTypes).
+                return new Il2Cpp.Image(
+                    this.object
+                        .method<Il2Cpp.Object>("GetType", 1)
+                        .invoke(Il2Cpp.string("<Module>"))
+                        .method<Il2Cpp.Object>("get_Module")
+                        .invoke()
+                        .field<NativePointer>("_impl").value
+                );
             }
 
-            getter(Il2Cpp.Assembly.prototype, "image", get, lazy);
-
-            return this.image;
+            return new Il2Cpp.Image(Il2Cpp.exports.assemblyGetImage(this));
         }
 
         /** Gets the name of this assembly. */

lib/structs/thread.ts

@@ -133,11 +133,7 @@ namespace Il2Cpp {
     /** Gets the attached threads. */
     export declare const attachedThreads: Il2Cpp.Thread[];
     getter(Il2Cpp, "attachedThreads", () => {
-        try {
-            Il2Cpp.exports.threadGetAttachedThreads;
-        } catch (error: any) {
-            if (error.name != "Il2CppError") throw error;
-
+        if (Il2Cpp.exports.threadGetAttachedThreads.isNull()) {
             const currentThreadHandle = Il2Cpp.currentThread?.handle ?? raise("Current thread is not attached to IL2CPP");
             const pattern = currentThreadHandle.toMatchPattern();
 

lib/structs/type.ts

@@ -161,11 +161,11 @@ namespace Il2Cpp {
         }
 
         is(other: Il2Cpp.Type): boolean {
-            try {
-                return !!Il2Cpp.exports.typeEquals(this, other);
-            } catch (_) {
+            if (Il2Cpp.exports.typeEquals.isNull()) {
                 return this.object.method<boolean>("Equals").invoke(other.object);
             }
+
+            return !!Il2Cpp.exports.typeEquals(this, other);
         }
 
         /** */