Type fixes for main (and the files main depends on) (#424)

## Summary

Type fixes.

---

- [x] "I certify that all code in this PR is my own, except as noted
below."

## Use of AI

- [ ] Includes AI-assisted code completion
- [ ] Includes code generated by an AI application
- [ ] Includes AI-generated tests (NOTE: AI written tests should have a
docstring that includes `## WRITTEN BY AI ##`)

Author: jaredoconnell

src/guidellm/__main__.py

@@ -33,7 +33,7 @@
 try:
     import uvloop
 except ImportError:
-    uvloop = None
+    uvloop = None # type: ignore[assignment] # Optional dependency
 
 from guidellm.backends import BackendType
 from guidellm.benchmark import (
@@ -124,7 +124,7 @@ def benchmark():
             dir_okay=False,
             path_type=Path,
         ),
-        click.Choice(get_builtin_scenarios().keys()),
+        click.Choice(tuple(get_builtin_scenarios().keys())),
     ),
     default=None,
     help=(

src/guidellm/benchmark/schemas.py

@@ -12,6 +12,7 @@
 
 from __future__ import annotations
 
+import inspect
 import json
 import random
 import time
@@ -1140,7 +1141,8 @@ def update_estimate(
             else None
         )
         request_duration = (
-            request_end_time - request_start_time if request_end_time else None
+            (request_end_time - request_start_time)
+            if request_end_time and request_start_time else None
         )
 
         # Always track concurrency
@@ -1791,7 +1793,7 @@ def create(
         return cls.model_validate(constructor_kwargs)
 
     @classmethod
-    def get_default(cls: BenchmarkGenerativeTextArgs, field: str) -> Any:
+    def get_default(cls: type[BenchmarkGenerativeTextArgs], field: str) -> Any:
         """
         Get default value for a model field.
 
@@ -1805,10 +1807,17 @@ def get_default(cls: BenchmarkGenerativeTextArgs, field: str) -> Any:
             )
 
         field_info = BenchmarkGenerativeTextArgs.model_fields[field]
-        if field_info.default_factory is not None:
-            return field_info.default_factory()
+        factory = field_info.default_factory
+
+        if factory is None:
+            return field_info.default
+
+        if len(inspect.signature(factory).parameters) == 0:
+            return factory()  # type: ignore[call-arg] # Confirmed correct at runtime by code above
+        else:
+            return factory({})  # type: ignore[call-arg] # Confirmed correct at runtime by code above
+
 
-        return field_info.default
 
     model_config = ConfigDict(
         extra="ignore",