Description:
A call to GetChars on a longtext column throws an exception.

How to repeat:
Build an IDataReader with a simple select command:

SELECT content from contents where contentid = X

where "content" is a longtext column.

Attempt to read data from the reader using GetChars.  An exception is thrown:

An unhandled exception of type 'MySql.Data.MySqlClient.MySqlException' occurred in
mysql.data.dll

Additional information: GetBytes can only be called on binary columns

Note that the method called is GetChars; the exception refers to GetBytes.

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