refactor: add new functions

Makefile

@@ -11,7 +11,7 @@ SOURCES = src/execute/execute_utils.c src/builtin/cd.c src/builtin/exit.c src/bu
  src/builtin/env.c src/builtin/pwd.c  src/builtin/builtin.c src/builtin/unset.c get_next_line/get_next_line.c \
  src/expander/expander_nonvariables.c src/env/env_utils.c src/lexer/utils.c src/handler.c src/env/env.c\
  src/lexer/lexer.c src/lexer/unquote.c src/lexer/lexer_utils.c src/parser.c src/execute/execute.c \
- src/execute/error_message.c src/execute/dup2.c src/execute/heredoc.c src/expander/expander.c src/splitter.c src/lexer/syntax_analyzer.c src/signal.c $(MEMORY_ALLOCATOR_SOURCES)
+  src/lexer/lexer_error_message.c src/lexer/is_valid.c src/execute/error_message.c src/execute/dup2.c src/execute/heredoc.c src/expander/expander.c src/splitter.c src/lexer/syntax_analyzer.c src/signal.c $(MEMORY_ALLOCATOR_SOURCES)
 
 MINISHELL_SOURCES = src/main.c $(SOURCES)
 MINISHELL_OBJECTS = $(MINISHELL_SOURCES:.c=.o)