[Bug]: [GoSDK] panic: assignment to entry in nil map when new AnnRequest with SearchParam

[ThreadDao]

Is there an existing issue for this?

• I have searched the existing issues

Environment

- Milvus version:
- Deployment mode(standalone or cluster):
- MQ type(rocksmq, pulsar or kafka):    
- SDK version(e.g. pymilvus v2.0.0rc2):go sdk v2
- OS(Ubuntu or CentOS): 
- CPU/Memory: 
- GPU: 
- Others:

Current Behavior

• hybrid search NewAnnRequest

	annReq1 := client.NewAnnRequest(common.DefaultFloatVecFieldName, common.DefaultLimit, queryVec1...).WithSearchParam("ef", "100")

• client log:

--- FAIL: TestHybridSearchDefault (5.51s)
panic: assignment to entry in nil map [recovered]
	panic: assignment to entry in nil map

goroutine 136 [running]:
testing.tRunner.func1.2({0xf6ea00, 0x127e6b0})
	/usr/local/go/src/testing/testing.go:1631 +0x24a
testing.tRunner.func1()
	/usr/local/go/src/testing/testing.go:1634 +0x377
panic({0xf6ea00?, 0x127e6b0?})
	/usr/local/go/src/runtime/panic.go:770 +0x132
github.com/milvus-io/milvus/client/v2/milvusclient.(*annRequest).WithSearchParam(...)
	/home/zong/zong/projects/milvus/client/milvusclient/read_options.go:249
github.com/milvus-io/milvus/tests/go_client/testcases.TestHybridSearchDefault(0xc00033a820)
	/home/zong/zong/projects/milvus/tests/go_client/testcases/hybrid_search_test.go:30 +0x40f
testing.tRunner(0xc00033a820, 0x11663f8)
	/usr/local/go/src/testing/testing.go:1689 +0xfb
created by testing.(*T).Run in goroutine 1
	/usr/local/go/src/testing/testing.go:1742 +0x390
FAIL	github.com/milvus-io/milvus/tests/go_client/testcases	5.550s

• case:

func TestHybridSearchDefault(t *testing.T) {
	t.Parallel()
	ctx := hp.CreateContext(t, time.Second*common.DefaultTimeout)
	mc := createDefaultMilvusClient(ctx, t)

	// create -> insert [0, 3000) -> flush -> index -> load
	prepare, schema := hp.CollPrepare.CreateCollection(ctx, t, mc, hp.NewCreateCollectionParams(hp.Int64Vec), hp.TNewFieldsOption(), hp.TNewSchemaOption())
	prepare.InsertData(ctx, t, mc, hp.NewInsertParams(schema), hp.TNewDataOption())
	prepare.FlushData(ctx, t, mc, schema.CollectionName)
	prepare.CreateIndex(ctx, t, mc, hp.TNewIndexParams(schema))
	prepare.Load(ctx, t, mc, hp.NewLoadParams(schema.CollectionName))

	// hybrid search
	queryVec1 := hp.GenSearchVectors(common.DefaultNq, common.DefaultDim, entity.FieldTypeFloatVector)
	queryVec2 := hp.GenSearchVectors(common.DefaultNq, common.DefaultDim, entity.FieldTypeFloatVector)
	annReq1 := client.NewAnnRequest(common.DefaultFloatVecFieldName, common.DefaultLimit, queryVec1...).WithSearchParam("ef", "100")
	annReq2 := client.NewAnnRequest(common.DefaultFloatVecFieldName, common.DefaultLimit, queryVec2...)

	searchRes, errSearch := mc.HybridSearch(ctx, client.NewHybridSearchOption(schema.CollectionName, common.DefaultLimit, annReq1, annReq2).WithOutputFields("*"))
	common.CheckErr(t, errSearch, true)
	common.CheckSearchResult(t, searchRes, common.DefaultNq, common.DefaultLimit)
	common.CheckOutputFields(t, []string{common.DefaultInt64FieldName, common.DefaultFloatVecFieldName}, searchRes[0].Fields)
}

Expected Behavior

No response

Steps To Reproduce

Milvus Log

No response

Anything else?

No response