patch 8.2.0706: Vim9: using assert_fails() causes function to finish

Problem:    Vim9: using assert_fails() causes function to finish.
Solution:   Check did_emsg instead of called_emsg.
diff --git a/src/vim9execute.c b/src/vim9execute.c
index cc677b0..a505647 100644
--- a/src/vim9execute.c
+++ b/src/vim9execute.c
@@ -458,7 +458,7 @@
 {
     typval_T	argvars[MAX_FUNC_ARGS];
     int		idx;
-    int		called_emsg_before = called_emsg;
+    int		did_emsg_before = did_emsg;
 
     if (call_prepare(argcount, argvars, ectx) == FAIL)
 	return FAIL;
@@ -470,7 +470,7 @@
     for (idx = 0; idx < argcount; ++idx)
 	clear_tv(&argvars[idx]);
 
-    if (called_emsg != called_emsg_before)
+    if (did_emsg != did_emsg_before)
 	return FAIL;
     return OK;
 }