Remove error message when exiting --stdin mode (#4368)

fix #4361
1. Remove error message when input a empty string
2. Remove error message when read input from stream
2. Remove error message when interrupt by `CTRL-C`

dvc/command/check_ignore.py

@@ -38,12 +38,11 @@ class CmdCheckIgnore(CmdBase):
     def _interactive_mode(self):
         ret = 1
         while True:
-            target = ask("")
+            try:
+                target = ask("")
+            except (KeyboardInterrupt, EOFError):
+                break
             if target == "":
-                logger.info(
-                    "Empty string is not a valid pathspec. Please use . "
-                    "instead if you meant to match all paths."
-                )
                 break
             if not self._check_one_file(target):
                 ret = 0