What does a specific EK9 error code mean?

  ek9 -h E50030

  E01010: Invalid identifier name
  E01020: Reserved word used as identifier
  E01030: Excluded keyword (break, continue, return do not exist in EK9)

  E02010: Duplicate type definition
  E02020: Duplicate method or property name
  E02030: Duplicate module definition

  E04010: Type must extend Exception (for throw/catch)
  E04020: Not a valid candidate for this context

  E05020: Circular type hierarchy detected
  E05030: Type is not open for extension (closed by default)
  E05120: Method must use override keyword (overriding base method)

  E06260: Parameter type mismatch
  E06280: Too many parameters for this operator or method
  E06290: Too few parameters
  E06330: Function signature does not match

  E07500: Operator must be pure but is not declared pure
  E07510: Operator cannot be pure (mutation operators)
  E07520: Incorrect return type for operator
  E07550: Comparison operator must return Boolean
  E07570: Hash operator must return Integer
  E07580: String operator must return String
  E07620: Operator not defined on this type

  E08020: Variable used before it is initialised
  E08030: Variable not checked with ? before access
  E08050: Return variable not initialised on all paths
  E08190: Circular dependency injection detected

  E11031: Variable name matches common convention violation
  E11032: Variable name is a reserved word
  E11040: Method complexity exceeds threshold

  E50030: Symbol not resolved (variable, type, method, or function not found)

  E50030: Check spelling and ensure imports are correct
  E05030: Mark the base type 'as open' if you intend to extend it
  E08020: Initialise the variable before using it
  E06280/E06290: Check operator parameter counts

defines module qa.debugging.errorcodelookup

  defines class

    Account
      name <- String()
      balance <- Float()

      Account()
        ->
          accountName as String
          initialBalance as Float
        require accountName?
        require initialBalance?
        require initialBalance >= 0.0
        this.name :=: accountName
        this.balance :=: initialBalance

      deposit()
        -> amount as Float
        require amount?
        require amount > 0.0
        balance += amount

      getBalance() as pure
        <- rtn as Float: balance

      operator $ as pure
        <- rtn as String: `Account(${name}, ${balance})`

      operator == as pure
        -> other as Account
        <- rtn as Boolean: name == other.name

      operator <=> as pure
        -> other as Account
        <- rtn as Integer: balance <=> other.balance

      override operator ? as pure
        <- rtn as Boolean: name? and balance?

  defines program

    ErrorCodeDemo()
      stdout <- Stdout()

      // Correctly constructed class with operators
      acc <- Account("Alice", 100.0)
      stdout.println(`Account: ${acc}`)

      acc.deposit(50.0)
      stdout.println(`After deposit: ${acc}`)
      stdout.println(`Balance: ${acc.getBalance()}`)

      // Correct comparison usage
      acc2 <- Account("Bob", 200.0)
      stdout.println(`Equal: ${acc == acc2}`)
      stdout.println(`Compare: ${acc <=> acc2}`)

acc.withdraw(50.0)

acc.deposit(50.0)

balance <- acc.getBalance()

stdout.println(`Balance: ${acc.getBalance()}`)