metal : handle nil cv during pipeline creation (#16065)

ggml-ci

ggml/src/ggml-metal/ggml-metal-device.m

@@ -327,12 +327,19 @@ ggml_metal_pipeline_t ggml_metal_library_compile_pipeline(ggml_metal_library_t l
 
         GGML_LOG_DEBUG("%s: compiling pipeline: base = '%s', name = '%s'\n", __func__, base, name);
 
-        id<MTLFunction> mtl_function = [lib->obj newFunctionWithName:base_func constantValues:(cv ? cv->obj : nil) error:&error];
+        id<MTLFunction> mtl_function;
+        if (!cv) {
+            mtl_function = [lib->obj newFunctionWithName:base_func];
+        } else {
+            mtl_function = [lib->obj newFunctionWithName:base_func constantValues:cv->obj error:&error];
+        }
         if (!mtl_function) {
             ggml_critical_section_end();
 
             GGML_LOG_ERROR("%s: error: failed to compile pipeline: base = '%s', name = '%s'\n", __func__, base, name);
-            GGML_LOG_ERROR("%s: error: %s\n", __func__, [[error description] UTF8String]);
+            if (error) {
+                GGML_LOG_ERROR("%s: error: %s\n", __func__, [[error description] UTF8String]);
+            }
 
             return nil;
         }