glsl: Add missing return error_value(ctx) in error path.

Reviewed-by: Chad Versace <chad.versace@linux.intel.com>
Reviewed-by: Ian Romanick <ian.d.romainck@intel.com>

src/glsl/ast_function.cpp

@@ -690,6 +690,7 @@ process_array_constructor(exec_list *instructions,
 			  "expected: %s, found %s",
 			  constructor_type->element_type()->name,
 			  result->type->name);
+         return ir_rvalue::error_value(ctx);
       }
 
       /* Attempt to convert the parameter to a constant valued expression.