EdiSerializer::DeserializeInternal use of reader before null check

SuppressBadEscapeSequenceErrors is set before the subsequent check for NULL on the reader.

This fix also includes a little cleanup of things like misspelled comments. 😄

Start at EdiSerializer::DeserializeInternal and inspect the order of operations around SuppressBadEscapeSequenceErrors and the reader null check. Confirm the fix prevents reader use before validation, then review the nearby comments for the noted spelling cleanup and verify the existing serializer behavior.

Written by the indexing model from the issue text.