Fix import extend class (#4)

* Fix import extend class

yea

* Update Interp.hx

* Fix issues with compiling

* Improved extend Errors

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Co-authored-by: NeeEoo <NeeEoo@users.noreply.github.com>

hscript/CustomClassHandler.hx

@@ -25,6 +25,9 @@ class CustomClassHandler implements IHScriptCustomConstructor {
 		interp.errorHandler = ogInterp.errorHandler;
 
 		var cl = extend == null ? TemplateClass : Type.resolveClass('${extend}_HSX');
+		if(cl == null)
+			ogInterp.error(EInvalidClass(extend));
+
 		var _class = Type.createInstance(cl, args);
 
 		var __capturedLocals = ogInterp.duplicate(ogInterp.locals);