add a typed exception

for accessing stuff through CALLER that is not dynamic

src/core/Exception.pm

@@ -1281,6 +1281,13 @@ my class X::Multi::NoMatch is Exception {
     }
 }
 
+my class X::Caller::NotDynamic is Exception {
+    has $.symbol;
+    method message() {
+        "Cannot access '$.symbol' through CALLER, because it is not declared as dynamic";
+    }
+}
+
 {
     my %c_ex;
     %c_ex{'X::TypeCheck::Binding'} := sub ($got, $expected) is hidden_from_backtrace {

src/core/PseudoStash.pm

@@ -1,4 +1,5 @@
 my class X::Bind { ... }
+my class X::Caller::NotDynamic { ... }
 
 my class PseudoStash is EnumMap {
     has Mu $!ctx;
@@ -119,7 +120,9 @@ my class PseudoStash is EnumMap {
                 if !$res.VAR.dynamic
                   && nqp::substr($nkey, 1, 1) ne '*'
                   && $key ne '$_' && $key ne '$/' && $key ne '$!' {
-                    die "You're trying to access $key through CALLER, but it is not dynamic."
+                    X::Caller::NotDynamic.new(
+                        symbol => $key,
+                    ).throw;
                 }
             }
             $res;