fix(nvim): Check for empty job runner output in async_check. (#297)

* fix(nvim): Handle `nil` output for `jobrunner` in `check`

* Auto generate docs

* refactor(nvim): Use fallback in `flatten_table_to_string` for empty error

Author: Davidyz

doc/VectorCode-API.txt

@@ -59,8 +59,8 @@ This function queries VectorCode and returns an array of results.
     })
 <
 
-- `query_message`string or a list of strings, the query messages;
-- `opts`The following are the available options for this function (see |VectorCode-API-`setup(opts?)`| for details):
+- `query_message`: string or a list of strings, the query messages;
+- `opts`: The following are the available options for this function (see |VectorCode-API-`setup(opts?)`| for details):
 
 >lua
     {
@@ -71,7 +71,7 @@ This function queries VectorCode and returns an array of results.
     }
 <
 
-- `callback`a callback function that takes the result of the retrieval as the
+- `callback`: a callback function that takes the result of the retrieval as the
     only parameter. If this is set, the `query` function will be non-blocking and
     runs in an async manner. In this case, it doesn’t return any value and
     retrieval results can only be accessed by this callback function.
@@ -118,7 +118,7 @@ project. See the CLI manual for details <./cli.md>.
     require("vectorcode").check()
 <
 
-The following are the available options for this function: - `check_item`Only
+The following are the available options for this function: - `check_item`: Only
 supports `"config"` at the moment. Checks if a project-local config is present.
 Return value: `true` if passed, `false` if failed.
 
@@ -201,25 +201,25 @@ This function registers a buffer to be cached by VectorCode.
     })
 <
 
-The following are the available options for this function: - `bufnr`buffer
-number. Default: `0` (current buffer); - `opts`accepts a lua table with the
-following keys: - `project_root`a string of the path that overrides the
+The following are the available options for this function: - `bufnr`: buffer
+number. Default: `0` (current buffer); - `opts`: accepts a lua table with the
+following keys: - `project_root`: a string of the path that overrides the
 detected project root. Default: `nil`. This is mostly intended to use with the
 |VectorCode-API-user-command|, and you probably should not use this directly in
 your config. **If you’re using the LSP backend and did not specify this
 value, it will be automatically detected based on .vectorcode or .git. If this
-fails, LSP backend will not work**; - `exclude_this`whether to exclude the file
-you’re editing. Default: `true`; - `n_query`number of retrieved documents.
-Default: `1`; - `debounce`debounce time in milliseconds. Default: `10`; -
-`notify`whether to show notifications when a query is completed. Default:
-`false`; - `query_cb``fun(bufnr: integer):string|string[]`, a callback function
-that accepts the buffer ID and returns the query message(s). Default:
-`require("vectorcode.utils").make_surrounding_lines_cb(-1)`. See
+fails, LSP backend will not work**; - `exclude_this`: whether to exclude the
+file you’re editing. Default: `true`; - `n_query`: number of retrieved
+documents. Default: `1`; - `debounce`: debounce time in milliseconds. Default:
+`10`; - `notify`: whether to show notifications when a query is completed.
+Default: `false`; - `query_cb`: `fun(bufnr: integer):string|string[]`, a
+callback function that accepts the buffer ID and returns the query message(s).
+Default: `require("vectorcode.utils").make_surrounding_lines_cb(-1)`. See
 |VectorCode-API-this-section| for a list of built-in query callbacks; -
-`events`list of autocommand events that triggers the query. Default:
-`{"BufWritePost", "InsertEnter", "BufReadPost"}`; - `run_on_register`whether to
-run the query when the buffer is registered. Default: `false`; -
-`single_job`boolean. If this is set to `true`, there will only be one running
+`events`: list of autocommand events that triggers the query. Default:
+`{"BufWritePost", "InsertEnter", "BufReadPost"}`; - `run_on_register`: whether
+to run the query when the buffer is registered. Default: `false`; -
+`single_job`: boolean. If this is set to `true`, there will only be one running
 job for each buffer, and when a new job is triggered, the last-running job will
 be cancelled. Default: `false`.
 
@@ -232,10 +232,10 @@ This function queries VectorCode from cache.
     local query_results = cacher_backend.query_from_cache(0, {notify=false})
 <
 
-The following are the available options for this function: - `bufnr`buffer
-number. Default: current buffer; - `opts`accepts a lua table with the following
-keys: - `notify`boolean, whether to show notifications when a query is
-completed. Default: `false`;
+The following are the available options for this function: - `bufnr`: buffer
+number. Default: current buffer; - `opts`: accepts a lua table with the
+following keys: - `notify`: boolean, whether to show notifications when a query
+is completed. Default: `false`;
 
 Return value: an array of results. Each item of the array is in the format of
 `{path="path/to/your/code.lua", document="document content"}`.
@@ -254,17 +254,18 @@ project.
     )
 <
 
-The following are the available options for this function: - `check_item`any
+The following are the available options for this function: - `check_item`: any
 check that works with `vectorcode check` command. If not set, it defaults to
-`"config"`; - `on_success`a callback function that is called when the check
-passes; - `on_failure`a callback function that is called when the check fails.
+`"config"`; - `on_success`: a callback function that is called when the check
+passes; - `on_failure`: a callback function that is called when the check
+fails.
 
 
 CACHER_BACKEND.BUF_IS_REGISTERED(BUFNR?) ~
 
 This function checks if a buffer has been registered with VectorCode.
 
-The following are the available options for this function: - `bufnr`buffer
+The following are the available options for this function: - `bufnr`: buffer
 number. Default: current buffer. Return value: `true` if registered, `false`
 otherwise.
 
@@ -276,7 +277,7 @@ slightly different from `buf_is_registered`, because it does not guarantee
 VectorCode is actively caching the content of the buffer. It is the same as
 `buf_is_registered && not is_paused`.
 
-The following are the available options for this function: - `bufnr`buffer
+The following are the available options for this function: - `bufnr`: buffer
 number. Default: current buffer. Return value: `true` if enabled, `false`
 otherwise.
 
@@ -288,8 +289,8 @@ Returns the number of running jobs in the background.
 
 CACHER_BACKEND.MAKE_PROMPT_COMPONENT(BUFNR?, COMPONENT_CB?) ~
 
-Compile the retrieval results into a string. Parameters: - `bufnr`buffer
-number. Default: current buffer; - `component_cb`a callback function that
+Compile the retrieval results into a string. Parameters: - `bufnr`: buffer
+number. Default: current buffer; - `component_cb`: a callback function that
 formats each retrieval result, so that you can customise the control token,
 etc. for the component. The default is the following:
 
@@ -299,8 +300,8 @@ etc. for the component. The default is the following:
     end
 <
 
-`make_prompt_component` returns a table with 2 keys: - `count`number of
-retrieved documents; - `content`The retrieval results concatenated together
+`make_prompt_component` returns a table with 2 keys: - `count`: number of
+retrieved documents; - `content`: The retrieval results concatenated together
 into a string. Each result is formatted by `component_cb`.
 
 
@@ -311,15 +312,15 @@ takes the buffer ID as the only parameter, and return a string or a list of
 strings. The `vectorcode.utils` module provides the following callback
 constructor for you to play around with it, but you can easily build your own!
 
-- `require("vectorcode.utils").make_surrounding_lines_cb(line_count)`returns a
+- `require("vectorcode.utils").make_surrounding_lines_cb(line_count)`: returns a
     callback that uses `line_count` lines around the cursor as the query. When
     `line_count` is negative, it uses the full buffer;
-- `require("vectorcode.utils").make_lsp_document_symbol_cb()`returns a
+- `require("vectorcode.utils").make_lsp_document_symbol_cb()`: returns a
     callback which uses the `textDocument/documentSymbol` method to retrieve a
     list of symbols in the current document. This will fallback to
     `make_surrounding_lines_cb(-1)` when there’s no LSP that supports the
     `documentSymbol` method;
-- `require("vectorcode.utils").make_changes_cb(max_num)`returns a callback
+- `require("vectorcode.utils").make_changes_cb(max_num)`: returns a callback
     that fetches `max_num` unique items from the `:changes` list. This will also
     fallback to `make_surrounding_lines_cb(-1)`. The default value for `max_num`
     is 50.