Ollama client doesn't like having non-text response of tool calling

[riywo]

It seems Ollama client doesn't like having non-text response of tool calling:

[2025-05-06 22:27:49.692 -0700] ERROR: LLM error: 1:llm:ChatOllama (3ms)
    error: "Non string tool message content is not supported\n\nError: Non string tool message content is not supported\n    at convertToolMessageToOllama (file:///Users/ryosuke.iwanaga/.npm/_npx/25982cb890102a2e/node_modules/aethr/node_modules/@langchain/ollama/dist/utils.js:119:15)\n    at file:///Users/ryosuke.iwanaga/.npm/_npx/25982cb890102a2e/node_modules/aethr/node_modules/@langchain/ollama/dist/utils.js:140:20\n    at Array.flatMap (<anonymous>)\n    at convertToOllamaMessages (file:///Users/ryosuke.iwanaga/.npm/_npx/25982cb890102a2e/node_modules/aethr/node_modules/@langchain/ollama/dist/utils.js:129:21)\n    at ChatOllama._streamResponseChunks (file:///Users/ryosuke.iwanaga/.npm/_npx/25982cb890102a2e/node_modules/aethr/node_modules/@langchain/ollama/dist/chat_models.js:730:32)\n    at _streamResponseChunks.next (<anonymous>)\n    at ChatOllama._generateUncached (file:///Users/ryosuke.iwanaga/.npm/_npx/25982cb890102a2e/node_modules/aethr/node_modules/@langchain/core/dist/language_models/chat_models.js:211:34)\n    at process.processTicksAndRejections (node:internal/process/task_queues:105:5)\n    at async ChatOllama.invoke (file:///Users/ryosuke.iwanaga/.npm/_npx/25982cb890102a2e/node_modules/aethr/node_modules/@langchain/core/dist/language_models/chat_models.js:88:24)\n    at async RunnableSequence.invoke (file:///Users/ryosuke.iwanaga/.npm/_npx/25982cb890102a2e/node_modules/aethr/node_modules/@langchain/core/dist/runnables/base.js:1280:27)"
[2025-05-06 22:27:49.694 -0700] INFO: Test result: FAIL, Summary:
Error: Non string tool message content is not supported

Previously, we had converted non-text response (array) to a text but dropped it by #2 since most of providers accept the array as-is.

ref. langchain-ai/langchainjs#8151