Don't choke on failed node name parsing

assets/.lua/schema.lua

@@ -11,7 +11,11 @@ end
 
 local function setup(db)
 	db:create_function("parse_node_name", 1, function(ctx, table_name)
-		local obj = csexp.parse(table_name)
+		local ok, obj = pcall(csexp.parse, table_name)
+		if not ok then
+			ctx:result_null()
+			return
+		end
 		if type(obj) ~= "table" or obj[1] ~= "node" then
 			ctx:result_null()
 			return

tests/test-schema.lua

@@ -44,4 +44,12 @@ describe("schema", function()
 			expect.equal(expected, actual)
 		end)
 	end)
+
+	describe("parse_node_name", function()
+		it("returns NULL on non-sexp table names", function()
+			for val in db:urows("SELECT parse_node_name('not a sexp')") do
+				expect.not_exist(val)
+			end
+		end)
+	end)
 end)