From 99207bc816d027b522e1c49001748c63fd426b53 Mon Sep 17 00:00:00 2001
From: EllangoK <ellangok@bxscience.edu>
Date: Wed, 18 Jan 2023 19:13:15 -0500
Subject: [PATCH 1/2] check model name values are set before merging

---
 modules/extras.py | 22 ++++++++++++++++++----
 1 file changed, 18 insertions(+), 4 deletions(-)

diff --git a/modules/extras.py b/modules/extras.py
index 22668fcda..29eb1f071 100644
--- a/modules/extras.py
+++ b/modules/extras.py
@@ -287,10 +287,19 @@ def run_modelmerger(primary_model_name, secondary_model_name, tertiary_model_nam
     def add_difference(theta0, theta1_2_diff, alpha):
         return theta0 + (alpha * theta1_2_diff)
 
+    if not primary_model_name:
+        shared.state.textinfo = "Failed: Merging requires a primary model."
+        shared.state.end()
+        return ["Failed: Merging requires a primary model."] + [gr.Dropdown.update(choices=sd_models.checkpoint_tiles()) for _ in range(4)]
+
     primary_model_info = sd_models.checkpoints_list[primary_model_name]
+
+    if not secondary_model_name:
+        shared.state.textinfo = "Failed: Merging requires a secondary model."
+        shared.state.end()
+        return ["Failed: Merging requires a secondary model."] + [gr.Dropdown.update(choices=sd_models.checkpoint_tiles()) for _ in range(4)]
+    
     secondary_model_info = sd_models.checkpoints_list[secondary_model_name]
-    tertiary_model_info = sd_models.checkpoints_list.get(tertiary_model_name, None)
-    result_is_inpainting_model = False
 
     theta_funcs = {
         "Weighted sum": (None, weighted_sum),
@@ -298,10 +307,15 @@ def run_modelmerger(primary_model_name, secondary_model_name, tertiary_model_nam
     }
     theta_func1, theta_func2 = theta_funcs[interp_method]
 
-    if theta_func1 and not tertiary_model_info:
+    tertiary_model_info = None
+    if theta_func1 and not tertiary_model_name:
         shared.state.textinfo = "Failed: Interpolation method requires a tertiary model."
         shared.state.end()
-        return ["Failed: Interpolation method requires a tertiary model."] + [gr.Dropdown.update(choices=sd_models.checkpoint_tiles()) for _ in range(4)]
+        return [f"Failed: Interpolation method ({interp_method}) requires a tertiary model."] + [gr.Dropdown.update(choices=sd_models.checkpoint_tiles()) for _ in range(4)]
+    else:
+        tertiary_model_info = sd_models.checkpoints_list.get(tertiary_model_name, None)
+
+    result_is_inpainting_model = False
 
     shared.state.textinfo = f"Loading {secondary_model_info.filename}..."
     print(f"Loading {secondary_model_info.filename}...")

From 26a6a78b16f88a6f88f4cca3f378db3b83fc94f8 Mon Sep 17 00:00:00 2001
From: EllangoK <karun.ellango7@gmail.com>
Date: Wed, 18 Jan 2023 21:21:52 -0500
Subject: [PATCH 2/2] only lookup tertiary model if theta_func1 is set

---
 modules/extras.py | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/modules/extras.py b/modules/extras.py
index 29eb1f071..88eea22ea 100644
--- a/modules/extras.py
+++ b/modules/extras.py
@@ -307,13 +307,12 @@ def run_modelmerger(primary_model_name, secondary_model_name, tertiary_model_nam
     }
     theta_func1, theta_func2 = theta_funcs[interp_method]
 
-    tertiary_model_info = None
     if theta_func1 and not tertiary_model_name:
         shared.state.textinfo = "Failed: Interpolation method requires a tertiary model."
         shared.state.end()
         return [f"Failed: Interpolation method ({interp_method}) requires a tertiary model."] + [gr.Dropdown.update(choices=sd_models.checkpoint_tiles()) for _ in range(4)]
-    else:
-        tertiary_model_info = sd_models.checkpoints_list.get(tertiary_model_name, None)
+    
+    tertiary_model_info = sd_models.checkpoints_list[tertiary_model_name] if theta_func1 else None
 
     result_is_inpainting_model = False