chore: make weight override more robust against ggml changes

Recently, GGML_TYPE_COUNT got bumped for the new GGML_TYPE_MXFP4
quant, getting it out-of-sync with SD_TYPE_COUNT.

To make it easier to build stable-diffusion.cpp against different
ggml versions, adjust the type conversions to consider both
GGML_TYPE_COUNT and SD_TYPE_COUNT as limits.

Author: wbruna

model.cpp

@@ -2156,7 +2156,7 @@ std::vector<std::pair<std::string, ggml_type>> parse_tensor_type_rules(const std
         if (type_name == "f32") {
             tensor_type = GGML_TYPE_F32;
         } else {
-            for (size_t i = 0; i < SD_TYPE_COUNT; i++) {
+            for (size_t i = 0; i < GGML_TYPE_COUNT; i++) {
                 auto trait = ggml_get_type_traits((ggml_type)i);
                 if (trait->to_float && trait->type_size && type_name == trait->type_name) {
                     tensor_type = (ggml_type)i;

stable-diffusion.cpp

@@ -241,7 +241,9 @@ class StableDiffusionGGML {
         }
 
         LOG_INFO("Version: %s ", model_version_to_str[version]);
-        ggml_type wtype = (ggml_type)sd_ctx_params->wtype;
+        ggml_type wtype = (int)sd_ctx_params->wtype < std::min<int>(SD_TYPE_COUNT, GGML_TYPE_COUNT)
+                          ? (ggml_type)sd_ctx_params->wtype
+                          : GGML_TYPE_COUNT;
         if (wtype == GGML_TYPE_COUNT) {
             model_wtype = model_loader.get_sd_wtype();
             if (model_wtype == GGML_TYPE_COUNT) {
@@ -1211,11 +1213,14 @@ class StableDiffusionGGML {
 #define NONE_STR "NONE"
 
 const char* sd_type_name(enum sd_type_t type) {
-    return ggml_type_name((ggml_type)type);
+    if ((int) type < std::min<int>(SD_TYPE_COUNT, GGML_TYPE_COUNT)) {
+        return ggml_type_name((ggml_type)type);
+    }
+    return NONE_STR;
 }
 
 enum sd_type_t str_to_sd_type(const char* str) {
-    for (int i = 0; i < SD_TYPE_COUNT; i++) {
+    for (int i = 0; i < std::min<int>(SD_TYPE_COUNT, GGML_TYPE_COUNT); i++) {
         auto trait = ggml_get_type_traits((ggml_type)i);
         if (!strcmp(str, trait->type_name)) {
             return (enum sd_type_t)i;