tdf#139922 sw autocorr: don't return GetPrevPara if isEmpty

This fixes a LO 6.2 regression caused by
commit 4cf5a46f16dec8ce16c6662ce5c17903e28b8fa3.

Change-Id: I4aee8f4e79a40a8b8f82faa3e62dead80a952510
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/125037
Tested-by: Jenkins
Reviewed-by: Justin Luth <jluth@mail.com>
Reviewed-by: Michael Stahl <michael.stahl@allotropia.de>
(cherry picked from commit 59dc5d00b04927d07df2dcc3c17acfdc760d8765)
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/125144
diff --git a/sw/source/core/edit/acorrect.cxx b/sw/source/core/edit/acorrect.cxx
index 9a8e45c..5a7946d 100644
--- a/sw/source/core/edit/acorrect.cxx
+++ b/sw/source/core/edit/acorrect.cxx
@@ -356,8 +356,11 @@ OUString const* SwAutoCorrDoc::GetPrevPara(bool const bAtNormalPos)
        }
        sw::GotoPrevLayoutTextFrame(*m_pIndex, m_rEditSh.GetLayout());
    }
    if (pFrame && 0 == pFrame->GetTextNodeForParaProps()->GetAttrOutlineLevel())
    if (pFrame && !pFrame->GetText().isEmpty() &&
        0 == pFrame->GetTextNodeForParaProps()->GetAttrOutlineLevel())
    {
        pStr = & pFrame->GetText();
    }

    if( m_bUndoIdInitialized )
        m_bUndoIdInitialized = true;