Don't allow bools as variables for tuple destructuring.

src/ast/tuple_literal.cr

@@ -3,7 +3,7 @@ module Mint
     class TupleLiteral < Node
       getter items
 
-      def initialize(@items : Array(Expression) | Array(BoolLiteral),
+      def initialize(@items : Array(Expression),
                      @input : Data,
                      @from : Int32,
                      @to : Int32)

src/parsers/case_branch.cr

@@ -8,7 +8,6 @@ module Mint
           match =
             constant_access ||
               enum_destructuring ||
-              bool_tuple_literal ||
               tuple_destructuring ||
               array_destructuring ||
               expression

src/parsers/tuple_destructuring.cr

@@ -1,10 +1,13 @@
 module Mint
   class Parser
+    INVALID_VARIABLE_NAMES =
+      ["true", "false"]
+
     def tuple_destructuring : Ast::TupleDestructuring?
       start do |start_position|
         head = start do
           next unless char! '{'
-          value = tuple_destructuring || variable
+          value = tuple_destructuring || variable(true, INVALID_VARIABLE_NAMES)
           whitespace
           next if char.in?('|', '=') # Don't parse record or record update as tuple destructuring
           char! ','
@@ -15,7 +18,7 @@ module Mint
         next unless head
 
         parameters = [head] &+ list(terminator: '}', separator: ',') do
-          tuple_destructuring || variable
+          tuple_destructuring || variable(true, INVALID_VARIABLE_NAMES)
         end
 
         whitespace

src/parsers/tuple_literal.cr

@@ -1,26 +1,5 @@
 module Mint
   class Parser
-    def bool_tuple_literal
-      start do |start_position|
-        next unless char! '{'
-
-        whitespace
-        items = list(
-          terminator: '}',
-          separator: ','
-        ) { bool_literal }
-        whitespace
-
-        next unless char! '}'
-
-        Ast::TupleLiteral.new(
-          from: start_position,
-          items: items,
-          to: position,
-          input: data)
-      end
-    end
-
     def tuple_literal : Ast::TupleLiteral?
       start do |start_position|
         next unless char! '{'

src/parsers/variable.cr

@@ -45,14 +45,15 @@ module Mint
       variable(track) || raise error
     end
 
-    def variable(track = true) : Ast::Variable?
+    def variable(track = true, invalid = [] of String) : Ast::Variable?
       start do |start_position|
         value = gather do
           next unless char.ascii_lowercase?
           letters_or_numbers
         end
 
         next unless value
+        next if value.in?(invalid)
 
         node = Ast::Variable.new(
           from: start_position,