patch 8.2.1753: Vim9: crash when using import at script level

Problem:    Vim9: crash when using import at script level.
Solution:   Give a "not implemented yet" error. (closes #7026)
diff --git a/src/evalvars.c b/src/evalvars.c
index 087a0cb..3571169 100644
--- a/src/evalvars.c
+++ b/src/evalvars.c
@@ -2486,6 +2486,11 @@
 		    rettv->vval.v_string = vim_strsave(import->imp_funcname);
 		}
 	    }
+	    else if (import->imp_all)
+	    {
+		emsg("Sorry, 'import * as X' not implemented yet");
+		ret = FAIL;
+	    }
 	    else
 	    {
 		scriptitem_T    *si = SCRIPT_ITEM(import->imp_sid);