[vala/0.46] vala: Method representing a LambdaExpression might be null on an error

[Rico Tzschichholz <ricotz src gnome org>]

commit eaf7a23ecc142d2c29286d5912e590d90a3acdbc
Author: Princeton Ferro <princetonferro gmail com>
Date:   Wed Feb 19 14:43:00 2020 +0100

    vala: Method representing a LambdaExpression might be null on an error
    
    This caused criticals like:
    
      vala_method_get_closure: assertion 'self != NULL' failed

 vala/valalambdaexpression.vala | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
---
diff --git a/vala/valalambdaexpression.vala b/vala/valalambdaexpression.vala
index a22497e70..0c55568ac 100644
--- a/vala/valalambdaexpression.vala
+++ b/vala/valalambdaexpression.vala
@@ -249,7 +249,7 @@ public class Vala.LambdaExpression : Expression {
 
        public override void get_used_variables (Collection<Variable> collection) {
                // require captured variables to be initialized
-               if (method.closure) {
+               if (method != null && method.closure) {
                        method.get_captured_variables ((Collection<LocalVariable>) collection);
                }
        }