Removed redundant code for handling None input and added check for empty input.

aider/coder.py

@@ -179,8 +179,6 @@ class Coder:
             print()
 
         inp = get_input(self.history_file, self.fnames)
-        if inp is None:
-            return
 
         self.num_control_c = 0
 
@@ -195,6 +193,9 @@ class Coder:
             ]
             self.cur_messages = []
 
+        if not inp:
+            return
+
         self.cur_messages += [
             dict(role="user", content=inp),
         ]