relax chunk parsing and fail on other chunks that fail to parse (fix for ollama)

Author: leafo

openai/init.lua

@@ -67,7 +67,7 @@ local parse_completion_chunk = types.partial({
   object = "chat.completion.chunk",
   choices = types.shape({
     types.partial({
-      delta = types.shape({
+      delta = types.partial({
         ["content"] = types.string:tag("content")
       }),
       index = types.number:tag("index")
@@ -243,7 +243,7 @@ do
             end
             accumulation_buffer = rest
             do
-              chunk = parse_completion_chunk(cjson.decode(json_blob))
+              chunk = assert(parse_completion_chunk(cjson.decode(json_blob)))
               if chunk then
                 chunk_callback(chunk)
               end

openai/init.moon

@@ -89,7 +89,7 @@ parse_completion_chunk = types.partial {
   -- not sure of the whole range of chunks, so for now we strictly parse an append
   choices: types.shape {
     types.partial {
-      delta: types.shape {
+      delta: types.partial {
         "content": types.string\tag "content"
       }
       index: types.number\tag "index"
@@ -253,7 +253,7 @@ class OpenAI
             break
 
           accumulation_buffer = rest
-          if chunk = parse_completion_chunk cjson.decode json_blob
+          if chunk = assert parse_completion_chunk cjson.decode json_blob
             chunk_callback chunk
 
       ...