allow tools args to be an empty string

Sources/Converse/ContentBlocks/JSON.swift

@@ -60,7 +60,13 @@ public struct JSON: Codable, @unchecked Sendable {  // FIXME: make Sendable
     }
 
     public init(from string: String) throws {
-        guard let data = string.data(using: .utf8) else {
+        var s: String!
+        if string.isEmpty {
+            s = "{}"
+        } else {
+            s = string
+        }
+        guard let data = s.data(using: .utf8) else {
             throw BedrockLibraryError.encodingError("Could not encode String to Data")
         }
         try self.init(from: data)

Sources/Converse/Streaming/ConverseReplyStream.swift

@@ -267,10 +267,9 @@ public struct ConverseReplyStream: Sendable {
         //     contentBlock[currentBlockId] = .reasoning(bufferReasoningData)
         //     bufferReasoningData = Data()
         // }
-        if !state.bufferToolUse.isEmpty {
-            guard let toolUseStart = state.toolUseStart else {
-                throw BedrockLibraryError.invalidSDKType("Received a tool use delta without tool use start")
-            }
+
+        // when there is a toolUse, the bufferToolUse may be empty, when the model found out that there is not arguments to pass. Therefore, I just check the presence of the toolUseStart
+        if let toolUseStart = state.toolUseStart {
             let json = try JSON(from: state.bufferToolUse)
             state.lastContentBlock = (
                 state.currentBlockId, .toolUse(.init(id: toolUseStart.id, name: toolUseStart.name, input: json))

Tests/Converse/JSONTests.swift

@@ -18,7 +18,8 @@ import Testing
 @testable import BedrockService
 
 // MARK: JSON
-extension BedrockServiceTests {
+@Suite("JSONTests")
+struct JSONTests {
 
     @Test("JSON getValue")
     func jsonGetValue() async throws {
@@ -126,4 +127,12 @@ extension BedrockServiceTests {
             let _ = try JSON(from: invalidJSONString)
         }
     }
+
+    @Test("Empty JSON")
+    func emptyJSON() async throws {
+        #expect(throws: Never.self) {
+            let json = try JSON(from: "")
+            #expect(json.getValue("nonExistentKey") == nil)
+        }
+    }
 }