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erNullVariantError

erNullVariantError = 22

Example​

function IsNullVariantCategory(const ErrorType: TIFException): Boolean;
begin
  Result := ErrorType = erNullVariantError;
end;

Usage​

erNullVariantError retains the Velox scripting Null-Variant error category, although current runtime source has no explicit automatic producer.

Formatting and exception state​

ExceptionToString ignores Param and returns Null variant error. It remains possible to supply the member explicitly through RaiseException, but that does not reproduce a Velox Variant failure.

Additional Technical Info​

erNullVariantError is member ordinal 22 of TIFException, the script-visible declaration that is kept in exact ordinal alignment with PascalScript's runtime TPSError. Its sidebar position 33 is alphabetical navigation metadata and is not its enumeration value.

erNullVariantError is ordinal 22 in TIFException/TPSError and names an invalid operation involving a Null Variant. The current Velox PascalScript runtime declares and formats it but contains no explicit producer that assigns this category. A Delphi EVariantError raised inside a guarded imported/runtime operation normally reaches the generic erException branch unless a more specific PascalScript path handles it. Variant operations outside those guards can propagate according to their surrounding host boundary. Therefore this retained member must not be documented as the guaranteed result of every Null operation.

Behavior, recovery and quirks​

  • Use VarIsNull, explicit Null propagation rules and the called API's contract instead of relying on an exception category.
  • Absence of an automatic producer is intentional documentation of current source, not proof that the value can never appear from host code or compatibility bytecode.
  • Do not persist the ordinal as a durable error protocol.
  • Exception transfer is not a database, dataset, filesystem or external-system transaction. Any earlier side effect remains unless the called API or surrounding Flow provides an explicit rollback contract.
  • Do not persist the numeric ordinal as an integration contract. Store the member name, formatted message, parameter and relevant procedure/position with the Velox version.

Related Code Library entries

External references

Created 2026-07-15