syntax parsing error when declaring const hook

If you were to declare a top level constant hook and use it. You will get a build time error.
E.G.

const myHook = ChainedHook([]);

@MappableClass(hook: hook)
class Foo with FooMappable{
  final String? bar;
  Foo(this.bar)
}

The error was:
Could not format because the source could not be parsed:

line 122, column 40 of .: Expected to find '('.
    ╷
122 │         final MappingHook hook = const myHook ;
    │                                        ^^^^^^^^^^^^^^^^^
    ╵

There code here is not referring to the source code, it's referring to the code that dart_mappable created, before throwing it away once it detected a syntax error.

The issue here is that const should only appear when instantiating a Hook, not when referencing a constant.

@schultek Seems like a simple check here should suffice:

dart_mappable/packages/dart_mappable_builder/lib/src/generators/mixins/decoding_mixin.dart

Lines 11 to 17 in 4777e79

    
               var hook = element.hookForClass; 
        
               if (hook != null) { 
        
                 output.write(''' 
        
                   @override 
        
                   final MappingHook hook = const $hook; 
        
                 '''); 
        
               }

Indeed a bug, let me look into it.

	var hook = element.hookForClass;
	if (hook != null) {
	output.write('''
	@override
	final MappingHook hook = const $hook;
	''');
	}