Abandon type overload

mypy is being silly here, and I don't want a 100 lines of type
overloads.

lib/galaxy/web/framework/middleware/error.py

@@ -16,7 +16,6 @@
 from typing import (
     cast,
     Optional,
-    overload,
 )
 
 import markupsafe
@@ -29,7 +28,6 @@
     formatter,
     reporter,
 )
-from typing_extensions import Literal
 
 log = logging.getLogger(__name__)
 
@@ -199,7 +197,7 @@ def exception_handler(self, exc_info, environ) -> str:
             get_vars = wsgilib.parse_querystring(environ)
             if dict(get_vars).get(self.xmlhttp_key):
                 simple_html_error = True
-        return handle_exception(
+        rval = handle_exception(
             exc_info,
             environ["wsgi.errors"],
             html=True,
@@ -217,6 +215,8 @@ def exception_handler(self, exc_info, environ) -> str:
             simple_html_error=simple_html_error,
             environ=environ,
         )
+        rval = cast(str, rval)  # we know handle_exception returns string because html=True
+        return rval
 
 
 class ResponseStartChecker:
@@ -350,50 +350,6 @@ def extraData(self):
     }
 
 
-@overload
-def handle_exception(
-    exc_info,
-    error_stream,
-    html: Literal[False] = ...,
-    debug_mode=...,
-    error_email=...,
-    error_log=...,
-    show_exceptions_in_wsgi_errors=...,
-    error_email_from=...,
-    smtp_server=...,
-    smtp_username=...,
-    smtp_password=...,
-    smtp_use_tls=...,
-    error_subject_prefix=...,
-    error_message=...,
-    simple_html_error=...,
-    environ=...,
-) -> None:
-    ...
-
-
-@overload
-def handle_exception(
-    exc_info,
-    error_stream,
-    html: Literal[True] = True,
-    debug_mode=...,
-    error_email=...,
-    error_log=...,
-    show_exceptions_in_wsgi_errors=...,
-    error_email_from=...,
-    smtp_server=...,
-    smtp_username=...,
-    smtp_password=...,
-    smtp_use_tls=...,
-    error_subject_prefix=...,
-    error_message=...,
-    simple_html_error=...,
-    environ=...,
-) -> str:
-    ...
-
-
 def handle_exception(
     exc_info,
     error_stream,