fix: avoid crash loading LoRAs with bf16 weights (#1077)

Author: wbruna

ggml_extend.hpp

@@ -1400,10 +1400,14 @@ __STATIC_INLINE__ void ggml_ext_backend_tensor_get_and_sync(ggml_backend_t backe
 }
 
 __STATIC_INLINE__ float ggml_ext_backend_tensor_get_f32(ggml_tensor* tensor) {
-    GGML_ASSERT(tensor->type == GGML_TYPE_F32 || tensor->type == GGML_TYPE_F16 || tensor->type == GGML_TYPE_I32);
+    GGML_ASSERT(tensor->type == GGML_TYPE_F32 || tensor->type == GGML_TYPE_F16 || tensor->type == GGML_TYPE_I32 || tensor->type == GGML_TYPE_BF16);
     float value;
     if (tensor->type == GGML_TYPE_F32) {
         ggml_backend_tensor_get(tensor, &value, 0, sizeof(value));
+    } else if (tensor->type == GGML_TYPE_BF16) {
+        ggml_bf16_t bf16_value;
+        ggml_backend_tensor_get(tensor, &bf16_value, 0, sizeof(bf16_value));
+        value = ggml_bf16_to_fp32(bf16_value);
     } else if (tensor->type == GGML_TYPE_F16) {
         ggml_fp16_t f16_value;
         ggml_backend_tensor_get(tensor, &f16_value, 0, sizeof(f16_value));