avm1: tellTarget on an undefined object targets the base clip in SWF6-

core/src/avm1/activation.rs

@@ -1981,7 +1981,12 @@ impl<'a, 'gc> Activation<'a, 'gc> {
                 return self.set_target(&target);
             }
             Value::Undefined => {
-                self.set_target_clip(None);
+                // In SWF6 and below, SetTarget2 on an undefined object resets the target to the base clip
+                if self.swf_version() > 6 {
+                    self.set_target_clip(None);
+                } else {
+                    self.set_target_clip(Some(base_clip));
+                }
             }
             Value::Object(o) => {
                 if let Some(clip) = o.as_display_object() {

tests/tests/swfs/avm1/tell_target_invalid/output.txt

@@ -1,6 +1,6 @@
 Target not found: Target="dummy" Base="_level0.mc"
 /tellTarget('dummy') { gotoAndPlay(n); }
 pass
-/tellTarget(undefined) { gotoAndPlay(5); }
+/tellTarget(undefined) { gotoAndStop(5); }
 /tellTarget(undefined) { gotoAndPlay(n); }
 pass

tests/tests/swfs/avm1/tell_target_invalid_swf6/output.txt

@@ -0,0 +1,5 @@
+Target not found: Target="dummy" Base="_level0.mc"
+/tellTarget('dummy') { gotoAndPlay(n); }
+pass
+/tellTarget(undefined) { gotoAndStop(5); }
+This should only be reached in SWF6 and below

tests/tests/swfs/avm1/tell_target_invalid_swf6/test.toml

@@ -0,0 +1,3 @@
+# This test was compiled from the same source as `tell_target_invalid`.
+# The header was edited to SWF version 6 using JPEXS FFDec.
+num_frames = 5