Initialize Aster project with basic structure, including Cargo configuration, lexer, parser, interpreter, and AST definitions. Add a sample script and README documentation. Implement basic error handling and environment management for variable storage.

src/error/error.rs

@@ -0,0 +1,26 @@
+use crate::lexer::Token;
+
+#[derive(Debug)]
+pub enum RuntimeError {
+    ParseError { message: String, token: Token },
+    RuntimeError { message: String, token: Option<Token> },
+}
+
+impl std::fmt::Display for RuntimeError {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        match self {
+            RuntimeError::ParseError { message, token } => {
+                write!(f, "[Parse Error] {} at line {}, column {}", message, token.line, token.column)
+            }
+            RuntimeError::RuntimeError { message, token } => {
+                if let Some(tok) = token {
+                    write!(f, "[Runtime Error] {} at line {}, column {}", message, tok.line, tok.column)
+                } else {
+                    write!(f, "[Runtime Error] {}", message)
+                }
+            }
+        }
+    }
+}
+
+impl std::error::Error for RuntimeError {}

src/error/mod.rs

@@ -0,0 +1,3 @@
+pub mod error;
+
+pub use error::*;