improved error message

Author: dibyendumajumdar

parser/src/main/java/com/compilerprogramming/ezlang/parser/Parser.java

@@ -438,7 +438,7 @@ private AST.Expr parsePostfix(Lexer lexer, AST.Expr primaryExpr) {
                     matchPunctuation(lexer, ")");
                     prevExpr = new AST.CallExpr(prevExpr, args);
                 }
-                default -> throw new CompilerException("Syntax error");
+                default -> error(currentToken, "Syntax error: expected a postfix operator [ . or C");
             }
         }
         return prevExpr;