fix: skip empty metadata filter in RetrieverTool to prevent vector store error (#5976)

* fix: skip empty metadata filter in RetrieverTool to prevent vector store error

When a user adds an "Additional Metadata Filter" then removes it, the
empty filter object {} was still passed to the vector store, causing
Pinecone (and potentially others) to reject it with "You must enter a
filter object with at least one key-value pair." Now checks that the
resolved filter has at least one key before assigning it.

Fixes #4900

Signed-off-by: majiayu000 <1835304752@qq.com>

* fix: rename metadatafilter to metadataFilter for camelCase consistency

Signed-off-by: majiayu000 <1835304752@qq.com>

* Delete packages/components/nodes/tools/RetrieverTool/RetrieverTool.test.ts

---------

Signed-off-by: majiayu000 <1835304752@qq.com>
Co-authored-by: Henry Heng <henryheng@flowiseai.com>

Author: majiayu000

packages/components/nodes/tools/RetrieverTool/RetrieverTool.ts

@@ -197,12 +197,14 @@ class Retriever_Tools implements INode {
             if (retrieverToolMetadataFilter) {
                 const flowObj = flowConfig
 
-                const metadatafilter =
+                const metadataFilter =
                     typeof retrieverToolMetadataFilter === 'object' ? retrieverToolMetadataFilter : JSON.parse(retrieverToolMetadataFilter)
-                const newMetadataFilter = resolveFlowObjValue(metadatafilter, flowObj)
+                const newMetadataFilter = resolveFlowObjValue(metadataFilter, flowObj)
 
-                const vectorStore = (retriever as VectorStoreRetriever<any>).vectorStore
-                vectorStore.filter = newMetadataFilter
+                if (newMetadataFilter && typeof newMetadataFilter === 'object' && Object.keys(newMetadataFilter).length > 0) {
+                    const vectorStore = (retriever as VectorStoreRetriever<any>).vectorStore
+                    vectorStore.filter = newMetadataFilter
+                }
             }
             const docs = await retriever.invoke(input)
             const content = docs.map((doc) => doc.pageContent).join('\n\n')