Fix not being able to close the app during login flow

exceptions.py

@@ -1,4 +1,7 @@
 class MinerException(Exception):
+    """
+    Base exception class for this application.
+    """
     def __init__(self, *args: object):
         if args:
             super().__init__(*args)
@@ -6,7 +9,23 @@ class MinerException(Exception):
             super().__init__("Unknown miner error")
 
 
+class ExitRequest(MinerException):
+    """
+    Raised when the application is requested to exit from outside of the main loop.
+
+    Intended for internal use only.
+    """
+    def __init__(self, *args: object):
+        if args:
+            super().__init__(*args)
+        else:
+            super().__init__("Unknown error during request")
+
+
 class RequestException(MinerException):
+    """
+    Raised for cases where a web request doesn't return what we wanted it to.
+    """
     def __init__(self, *args: object):
         if args:
             super().__init__(*args)
@@ -15,6 +34,9 @@ class RequestException(MinerException):
 
 
 class LoginException(RequestException):
+    """
+    Raised when an exception occurs during login phase.
+    """
     def __init__(self, *args: object):
         if args:
             super().__init__(*args)
@@ -23,5 +45,8 @@ class LoginException(RequestException):
 
 
 class CaptchaRequired(LoginException):
+    """
+    The most dreaded thing about automated scripts.
+    """
     def __init__(self):
         super().__init__("Captcha is required")