Better error reporting of not mached parens

src/errors.cc

@@ -185,8 +185,10 @@ std::ostream& operator<<(std::ostream& os, Error const& err)
 
 			Lines::the.print(os, std::string(loc->filename), loc->line, loc->line);
 
-			os << pretty::begin_comment << "\nThis error is considered an internal one. It should not be displayed to the end user.\n" << pretty::end;
+			os << pretty::begin_comment << "\nThis error is considered an internal one. It should not be displayed to the end user.\n";
-			encourage_contact(os);
+			os << "\n";
+			os << "This error message is temporary and will be replaced by better one in the future\n";
+			os << pretty::end;
 		},
 
 		[&](errors::Expected_Expression_Separator_Before const& err) {

src/parser.cc

@@ -271,7 +271,10 @@ Result<Ast> Parser::parse_atomic_expression()
 							}
 						}
 					}
-					unimplemented("Don't know why it stopped, maybe end of file?");
+					return Error {
+						.details = errors::Unexpected_Empty_Source {},
+						.location = {}
+					};
 				}
 				consume();
 				if (is_lambda) {
@@ -287,7 +290,15 @@ Result<Ast> Parser::parse_atomic_expression()
 			consume();
 			auto ast = Try(parse_sequence());
 			if (not expect(Token::Type::Close_Paren)) {
-				unimplemented("Error handling of this code is not implemented yet");
+				auto const& token = Try(peek());
+				return Error {
+					.details = errors::internal::Unexpected_Token {
+						.type = type_name(token.type),
+						.source = token.source,
+						.when = "waiting for closing paren ')'"
+					},
+					.location = token.location
+				};
 			}
 			consume();
 			return ast;