improve error-reporting.

Doesn't make much sense to print that something went wrong, and then
only report it in the log.
Just throw and catch, and then print details.

lua/luasnip/extras/snip_location.lua

@@ -15,8 +15,7 @@ local M = {}
 local function lua_find_function_call_node_at(bufnr, line)
 	local has_parser, parser = pcall(vim.treesitter.get_parser, bufnr)
 	if not has_parser then
-		log.warn("Cannot determine range of function-call: treesitter-parser for lua not installed.")
-		return nil
+		error("treesitter-parser for lua not installed.")
 	end
 
 	local root = parser:parse()[1]:root()
@@ -26,8 +25,7 @@ local function lua_find_function_call_node_at(bufnr, line)
 			return {node:range()}
 		end
 	end
-	log.warn("Cannot determine range of function-call: Query for `(function_call)` starting at line %s did not yield a result.")
-	return nil
+	error("Query for `(function_call)` starting at line %s did not yield a result.")
 end
 
 local function range_highlight(line_start, line_end, hl_duration_ms)
@@ -51,17 +49,13 @@ local function range_highlight(line_start, line_end, hl_duration_ms)
 end
 
 local function json_find_snippet_definition(bufnr, snippet_name)
-	local has_parser, parser = pcall(vim.treesitter.get_parser, bufnr)
-	if not has_parser then
-		log.warn("Cannot determine definition of snippet: treesitter-parser for json(c) not installed.")
-		return nil
+	local parser_ok, parser = pcall(vim.treesitter.get_parser, bufnr)
+	if not parser_ok then
+		error("Cannot determine definition of snippet: treesitter-parser for jsonc) not installed.")
 	end
 
 	local root = parser:parse()[1]:root()
-	-- for a, b in root:child(0):iter_children() do
-	-- 	Insp(a:field("key")[1]:child(1):range())
-	-- end
-	-- don't want to pass through if this file is json or jsonc, just use
+	-- don't want to pass through whether this file is json or jsonc, just use
 	-- parser-language.
 	local query = vim.treesitter.parse_query(parser:lang(), ([[
 		(pair
@@ -70,11 +64,12 @@ local function json_find_snippet_definition(bufnr, snippet_name)
 	]]):format(snippet_name))
 	for id, node, _ in query:iter_captures(root, bufnr) do
 		if query.captures[id] == "snippet" and node:parent():parent() == root then
+			-- return first match.
 			return {node:range()}
 		end
 	end
 
-	return nil
+	error(("Treesitter did not find the definition for snippet `%s`"):format(snippet_name))
 end
 
 local function win_edit(file)
@@ -106,8 +101,10 @@ function M.jump_to_snippet(snip, opts)
 		if source.line then
 			-- in lua-file, can get region of definition via treesitter.
 			-- 0: current buffer.
-			fcall_range = lua_find_function_call_node_at(0, source.line-1)
-			if not fcall_range then
+			local ok
+			ok, fcall_range = pcall(lua_find_function_call_node_at, 0, source.line-1)
+			if not ok then
+				print("Could not determine range for snippet-definition: " .. fcall_range)
 				vim.api.nvim_win_set_cursor(0, {source.line, 0})
 				return
 			end
@@ -118,15 +115,23 @@ function M.jump_to_snippet(snip, opts)
 	-- matches *.json or *.jsonc.
 	elseif vim.api.nvim_buf_get_name(0):match("%.jsonc?$") then
 		-- 0: current buffer.
-		fcall_range = json_find_snippet_definition(0, snip.name)
-		if not fcall_range then
-			print("Could not find range of snippet `" .. snip.name .. "`.")
+		local ok
+		ok, fcall_range = pcall(json_find_snippet_definition, 0, snip.name)
+		if not ok then
+			print("Could not determine range of snippet-definition: " .. fcall_range)
 			return
 		end
 	else
-		print("Unknown filetype, don't know how to highlight snippet.")
+		print(("Don't know how to highlight snippet-definitions in current buffer `%s`.%s"):format(
+			vim.api.nvim_buf_get_name(0),
+			source.line ~= nil and " Jumping to `source.line`" or ""))
+
+		if source.line ~= nil then
+			vim.api.nvim_win_set_cursor(0, {source.line, 0})
+		end
 		return
 	end
+	assert(fcall_range ~= nil, "fcall_range is not nil")
 
 	-- 1 is line_from, 3 is line_end.
 	-- +1 since range is row-0-indexed.