every time i try to run a lua script it instantly closes

EVERY TIME I TRY TO RUN A LUA SCRIPT IT INSTANTLY CLOSES MANUAL
EVERY TIME I TRY TO RUN A LUA SCRIPT IT INSTANTLY CLOSES CODE

Invalid concatenation by '+' not '.' operator: my_str = my_str + 'z' - The concatenation operator is double-dot '.' and trying to use a plus-sign '+' might pass during the pre-compile of edit-save but hit 'Script error' when that portion of the Lua script is executed.'xx' - The string named 'my_str' must not be nil when used inside a string concatenation operation. Invalid concatenation of empty string: my_str = my_str.However, some errors are more common than others:

EVERY TIME I TRY TO RUN A LUA SCRIPT IT INSTANTLY CLOSES CODE

Clicking the error text displays a popup that includes the actual error message generated by Lua, which can be used in a search engine to find a thorough description of what the message means and common remedies, as well as a stack trace to help determine the part of the code that actually triggered the error. There can be many reasons why a Lua module triggers the message ' Script error' when run in another page.

Instead, it might be possible to use a lexical analysis tool, specifically for Lua script, to better detect and pinpoint misspelled variables or logic errors in Lua source code. Other pre-compiled, or semi-compiled, languages can pinpoint the line number, or code phrase, where a syntax error, or undefined variable name, has been detected however, that processing can require extra time to perform. Note: the saving of a working copy can be done to an offline text file, rather than saving each version into the module revisions. In general, make one small change at a time, do a run show-preview, and save after a few good changes to have a version to restore, in case terrible errors occur after numerous later changes. Also, unlike wp:templates which can be run interactively by edit-preview, the Lua script must be tested by show-preview (or run preview) of another page which uses a template which #invokes the Lua module being edited. Because Lua is a 'semi-compiled' interpreted language, it does not prescreen for all common syntax errors, nor detect misspelled variables, which are only found at runtime when seeing the ' Script error' message. This help-page, Help:Lua debugging, explains issues of writing Lua script and debugging the source code, to remove errors or improve performance.

EVERY TIME I TRY TO RUN A LUA SCRIPT IT INSTANTLY CLOSES MANUAL

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Every time i try to run a lua script it instantly closes