Update mixed_table warning message (#586)

Closes: #572 

It makes the error message for mixed tables more descriptive and
explains why they're bad and should be _avoided_.

---------

Co-authored-by: boyned//Kampfkarren <boynedmaster@gmail.com>
Co-authored-by: Chris Chang <51393127+chriscerie@users.noreply.github.com>

CHANGELOG.md

@@ -5,6 +5,9 @@ This project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.htm
 ### Added
 - Added `CFrame.lookAlong` to the Roblox standard library
 
+### Changed
+- Updated the warning message for the `mixed_table` lint to include why mixed tables should be avoided
+
 ## [0.26.1](https://github.com/Kampfkarren/selene/releases/tag/0.26.1) - 2023-11-11
 ### Fixed
 - Fixed `UDim2.new()` firing the [`roblox_suspicious_udim2_new` lint](https://kampfkarren.github.io/selene/lints/roblox_suspicious_udim2_new.html).

selene-lib/src/lints/mixed_table.rs

@@ -30,7 +30,7 @@ impl Lint for MixedTableLint {
         for mixed_table in visitor.mixed_tables {
             diagnostics.push(Diagnostic::new_complete(
                 "mixed_table",
-                "mixed tables are not allowed".to_owned(),
+                "mixed tables should be avoided, as they can cause confusing and hard to debug issues such as during iteration or encoding".to_owned(),
                 Label::new(mixed_table.range),
                 vec!["help: change this table to either an array or dictionary".to_owned()],
                 Vec::new(),

selene-lib/src/lints/roblox_incorrect_roact_usage.rs

@@ -18,7 +18,7 @@ use if_chain::if_chain;
 pub struct IncorrectRoactUsageLint;
 
 // Assumes string includes quotes at start and end
-fn is_lua_valid_table_key_identifier(string: &String) -> bool {
+fn is_lua_valid_table_key_identifier(string: &str) -> bool {
     // Valid identifier cannot start with numbers
     let first_char = string.chars().nth(1).unwrap();
     if !first_char.is_alphabetic() && first_char != '_' {

selene-lib/tests/lints/mixed_table/mixed_table.stderr

@@ -1,4 +1,4 @@
-error[mixed_table]: mixed tables are not allowed
+error[mixed_table]: mixed tables should be avoided, as they can cause confusing and hard to debug issues such as during iteration or encoding
   ┌─ mixed_table.lua:2:5
   │  
 2 │ ╭     "",
@@ -7,7 +7,7 @@ error[mixed_table]: mixed tables are not allowed
   │  
   = help: change this table to either an array or dictionary
 
-error[mixed_table]: mixed tables are not allowed
+error[mixed_table]: mixed tables should be avoided, as they can cause confusing and hard to debug issues such as during iteration or encoding
   ┌─ mixed_table.lua:7:5
   │  
 7 │ ╭     {},
@@ -16,7 +16,7 @@ error[mixed_table]: mixed tables are not allowed
   │  
   = help: change this table to either an array or dictionary
 
-error[mixed_table]: mixed tables are not allowed
+error[mixed_table]: mixed tables should be avoided, as they can cause confusing and hard to debug issues such as during iteration or encoding
    ┌─ mixed_table.lua:12:5
    │  
 12 │ ╭     a,
@@ -25,7 +25,7 @@ error[mixed_table]: mixed tables are not allowed
    │  
    = help: change this table to either an array or dictionary
 
-error[mixed_table]: mixed tables are not allowed
+error[mixed_table]: mixed tables should be avoided, as they can cause confusing and hard to debug issues such as during iteration or encoding
    ┌─ mixed_table.lua:19:5
    │  
 19 │ ╭     1,
@@ -34,7 +34,7 @@ error[mixed_table]: mixed tables are not allowed
    │  
    = help: change this table to either an array or dictionary
 
-error[mixed_table]: mixed tables are not allowed
+error[mixed_table]: mixed tables should be avoided, as they can cause confusing and hard to debug issues such as during iteration or encoding
    ┌─ mixed_table.lua:25:5
    │  
 25 │ ╭     [c] = d,
@@ -43,7 +43,7 @@ error[mixed_table]: mixed tables are not allowed
    │  
    = help: change this table to either an array or dictionary
 
-error[mixed_table]: mixed tables are not allowed
+error[mixed_table]: mixed tables should be avoided, as they can cause confusing and hard to debug issues such as during iteration or encoding
    ┌─ mixed_table.lua:30:5
    │  
 30 │ ╭     a = b,