Break down rustpython_parser::error module

because it doesn't share any common errors but specific error for each sub module

Author: youknowone

parser/python.lalrpop

@@ -5,7 +5,7 @@
 
 use crate::{
     ast,
-    error::{LexicalError, LexicalErrorType},
+    lexer::{LexicalError, LexicalErrorType},
     function::{ArgumentList, parse_args, parse_params, validate_arguments},
     lexer,
     context::set_context,

parser/src/error.rs

@@ -1,7 +1,7 @@
 // Contains functions that perform validation and parsing of arguments and parameters.
 // Checks apply both to functions and to lambdas.
 use crate::ast;
-use crate::error::{LexicalError, LexicalErrorType};
+use crate::lexer::{LexicalError, LexicalErrorType};
 use rustc_hash::FxHashSet;
 
 pub(crate) struct ArgumentList {
@@ -149,8 +149,8 @@ fn is_starred(exp: &ast::Expr) -> bool {
 
 #[cfg(test)]
 mod tests {
-    use crate::error::{LexicalErrorType, ParseErrorType};
-    use crate::parser::parse_program;
+    use crate::lexer::LexicalErrorType;
+    use crate::parser::{parse_program, ParseErrorType};
 
     macro_rules! function_and_lambda {
         ($($name:ident: $code:expr,)*) => {