patch 8.2.0370: the typebuf_was_filled flag is sometimes not reset

Problem:    The typebuf_was_filled flag is sometimes not reset, which may
            cause a hang.
Solution:   Make sure typebuf_was_filled is reset when the typeahead buffer is
            empty.
diff --git a/src/edit.c b/src/edit.c
index 70b8fee..edd2374 100644
--- a/src/edit.c
+++ b/src/edit.c
@@ -1612,6 +1612,10 @@
 	    // Match, consume the code.
 	    typebuf.tb_off += idx + 1;
 	    typebuf.tb_len -= idx + 1;
+#if defined(FEAT_CLIENTSERVER) || defined(FEAT_EVAL)
+	    if (typebuf.tb_len == 0)
+		typebuf_was_filled = FALSE;
+#endif
 
 	    mod_mask = decode_modifiers(arg[!form]);
 	    c = merge_modifyOtherKeys(arg[form]);