InitError is a helper function for easily initializing error object.

NewArgumentError is a helper function the helps initializing argument errors.

NewTypeParsingError is a helper function the helps initializing type parsing errors.

ArgumentError means there's a method parameter's definition error.

EndOfFileError represents normal EOF error.

InvalidAssignmentError means user assigns value to wrong type of expressions.

MethodDefinitionError means there's an error on method definition's method name.

SyntaxError means there's a grammatical error in the source code.

UnexpectedEndError means we get unexpected "end" keyword (this is mainly created for REPL).

UnexpectedEOFError means we got EOF when we expected another token.

UnexpectedTokenError means that token is not what we expected.

Error represents parser's parsing error.