Fix repl crash when deno dir doesn't exist (#2727)

cli/repl.rs

@@ -76,6 +76,14 @@ impl Repl {
   }
 
   fn save_history(&mut self) -> Result<(), ErrBox> {
+    if !self.history_dir_exists() {
+      eprintln!(
+        "Unable to save REPL history: {:?} directory does not exist",
+        self.history_file
+      );
+      return Ok(());
+    }
+
     self
       .editor
       .save_history(&self.history_file.to_str().unwrap())
@@ -86,6 +94,14 @@ impl Repl {
       })
   }
 
+  fn history_dir_exists(&self) -> bool {
+    self
+      .history_file
+      .parent()
+      .map(|ref p| p.exists())
+      .unwrap_or(false)
+  }
+
   pub fn readline(&mut self, prompt: &str) -> Result<String, ErrBox> {
     self
       .editor

tools/repl_test.py

@@ -11,7 +11,12 @@ class TestRepl(DenoTestCase):
     def input(self, *lines, **kwargs):
         exit_ = kwargs.pop("exit", True)
         sleep_ = kwargs.pop("sleep", 0)
-        p = Popen([self.deno_exe], stdout=PIPE, stderr=PIPE, stdin=PIPE)
+        env_ = kwargs.pop("env", None)
+        p = Popen([self.deno_exe],
+                  stdout=PIPE,
+                  stderr=PIPE,
+                  stdin=PIPE,
+                  env=env_)
         try:
             # Note: The repl takes a >100ms until it's ready.
             time.sleep(sleep_)
@@ -137,6 +142,14 @@ class TestRepl(DenoTestCase):
         self.assertEqual(err, '')
         self.assertEqual(code, 0)
 
+    def test_missing_deno_dir(self):
+        new_env = os.environ.copy()
+        new_env["DENO_DIR"] = os.path.abspath("doesnt_exist")
+        out, err, code = self.input("'noop'", exit=False, env=new_env)
+        self.assertEqual(out, "noop\n")
+        self.assertTrue(err.startswith("Unable to save REPL history:"))
+        self.assertEqual(code, 0)
+
 
 if __name__ == "__main__":
     run_tests()