fix a comment and clarify the error handler func a bit

using_xpcall.lua

@@ -53,6 +53,7 @@ end
 local function error_printer(err)
     log_add(err)
     log_add(debug.traceback("----------------------", 2))
+    return "error was logged"
 end
 
 
@@ -159,9 +160,10 @@ core.register_chatcommand(
 )
 
 -- This version allows us to get the error stack trace. We get the
--- trace by passing our helper function `error_printer` to xpcall.
--- (`error_printer` will be called on error without unwinding the
--- stack, so we can call `debug` functions to examine the error).
+-- trace by passing error handler function `error_printer` to xpcall.
+-- (our helper funciton, `error_printer` will be called on error
+-- without unwinding the stack, so we can call `debug` functions to
+-- examine the error).
 core.register_chatcommand(
     "bugged_safe2",
     {
@@ -170,7 +172,11 @@ core.register_chatcommand(
             -- NOTE: if this does not work, you may need to make sure you're using luajit or newer lua
             local status, ret1, ret2 = xpcall(bugged, error_printer, playername, params)
             -- `status` will be `false` if function call raised an error
-            -- `ret1` will contain the error message on error, or first returned value on no errors
+
+            -- `ret1` will contain first returned value in case of no
+            -- errors, or, in case of error, the value returned by the
+            -- error handler function.
+
             -- `ret2` will contain second returned value on no errors
             -- etc.
             return status, string.format("%s | %s", ret1, ret2)