MADB_StmtExecDirect() crashes if StatementText is "\0"

If MADB_StmtExecDirect get called with a StatementText "\0" (only TN contained) an exception occures in "char* FixIsoFormat(char * StmtString, size_t *Length)".
This causes the client application to crash.

Steps to reproduce:
WCHAR * StatementText = L"\0";
RetCode = SQLExecDirect(hStmt, StatementText, SQL_NTS);

or

1. Start odbct32w.exe from Microsoft Data Access SDK 2.8.
2. Choose from menu: Conn...Full connect (choose any Maria DSN)
3. Choose from menu: Stmt..SqlExecDirect
4. Choose "statment text=<empty string>" and "statement length=SQL_NTS=-3 (3.0)"
5. Press Ok
6. odbct32w.exe crashes

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This issue was originally observed when connecting via the Borland Database Engine (BDE).