Handle edge cases when generating embeddings (#1215)

* Handle edge cases when generating embeddings
* Improve Python handling & add llmodel_c.h note
- In the Python bindings fail fast with a ValueError when text is empty
- Advice other bindings authors to do likewise in llmodel_c.h

gpt4all-bindings/python/gpt4all/pyllmodel.py

@@ -251,6 +251,8 @@ class LLModel:
         self,
         text: str
     ) -> list[float]:
+        if not text:
+            raise ValueError("Text must not be None or empty")
         embedding_size = ctypes.c_size_t()
         c_text = ctypes.c_char_p(text.encode('utf-8'))
         embedding_ptr = llmodel.llmodel_embedding(self.model, c_text, ctypes.byref(embedding_size))

gpt4all-bindings/python/gpt4all/tests/test_gpt4all.py

@@ -3,6 +3,7 @@ from io import StringIO
 
 from gpt4all import GPT4All, Embed4All
 import time
+import pytest
 
 def test_inference():
     model = GPT4All(model_name='orca-mini-3b.ggmlv3.q4_0.bin')
@@ -107,3 +108,9 @@ def test_embedding():
     #for i, value in enumerate(output):
         #print(f'Value at index {i}: {value}')
     assert len(output) == 384
+
+def test_empty_embedding():
+    text = ''
+    embedder = Embed4All()
+    with pytest.raises(ValueError):
+        output = embedder.embed(text)