Initialise the BorderTitleBlock members its constructor compares

The constructor of BorderTitleBlock sets the border and title block
properties through importBorder() and importTitleBlock(). Their setters
(displayColumns(), setColumnsCount(), ...) compare the new value with
the member before storing it, and at that point the members have never
been written: display_columns_, display_rows_, the counts and sizes,
and m_edge are read uninitialised. UndefinedBehaviorSanitizer stops
every command-line run of the binary on the first of them:

  bordertitleblock.cpp:455:23: runtime error: load of value 190,
  which is not a valid value for type 'bool'
    #0 BorderTitleBlock::displayColumns(bool)
    #1 BorderTitleBlock::importBorder(BorderProperties const&)
    #2 BorderTitleBlock::BorderTitleBlock(QObject*)

Give those members a default value in the header: false, 0 and
Qt::BottomEdge. The constructor then compares against known values. No
behaviour changes: the only effect of the comparisons in the constructor
is a displayChanged() signal nobody is connected to yet, and the
defaults of BorderProperties and TitleBlockProperties are all non-zero,
so no setter skips its clamp.

No file-format change. Tests: the sanitizer build of the Linux CI job
(separate PR) fails on master with the report above and passes with
this change; ctest on macOS 56/57, the failure being tst_elementautonumids
as on master.

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>
Signed-off-by: Beat Hangartner <beat@hangartners.ch>

sources/bordertitleblock.h

@@ -254,38 +254,40 @@ class BorderTitleBlock : public QObject
 		QString btb_indexrev_;      ///< titleblock index rev
 		QString btb_final_folio_;   ///< titleblock final folio
 		QString btb_auto_page_num_; ///< titleblock auto page num
-		int folio_index_;           ///< titleblock index
-		int folio_total_;           ///< titleblock total
+		int folio_index_ = 0;       ///< titleblock index
+		int folio_total_ = 0;       ///< titleblock total
 		QString btb_filename_;      ///< titleblock filename
 		QString btb_version_;       ///< titleblock version
 		/// titleblock additional fields
 		DiagramContext additional_fields_;
-		Qt::Edge m_edge;              ///< titleblock edge
+		Qt::Edge m_edge = Qt::BottomEdge; ///< titleblock edge
 		QString m_next_folio_num;     ///< titleblock next folio num
 		QString m_previous_folio_num; ///< titleblock previous folio num
 	
 		// border dimensions (rows and columns)
 		// columns: number and dimensions
-		int columns_count_;           ///< columns count
-		qreal columns_width_;         ///< columns width
-		qreal columns_header_height_; ///< columns header height
+		int columns_count_ = 0;           ///< columns count
+		qreal columns_width_ = 0;         ///< columns width
+		qreal columns_header_height_ = 0; ///< columns header height
 	
 		// rows: number and dimensions
-		int rows_count_;          ///< rows count
-		qreal rows_height_;       ///< rows height
-		qreal rows_header_width_; ///< rows header width
+		int rows_count_ = 0;          ///< rows count
+		qreal rows_height_ = 0;       ///< rows height
+		qreal rows_header_width_ = 0; ///< rows header width
 	
 		// title block dimensions
-		qreal titleblock_height_;
+		qreal titleblock_height_ = 0;
 	
 		// rectangles used for drawing operations
 		QRectF diagram_rect_;
 	
-			// display options
-		bool display_titleblock_;
-		bool display_columns_;
-		bool display_rows_;
-		bool display_border_;
+		// display options. Initialised here because the constructor sets
+		// them through importBorder() and importTitleBlock(), whose setters
+		// compare the new value with the old one before storing it.
+		bool display_titleblock_ = false;
+		bool display_columns_ = false;
+		bool display_rows_ = false;
+		bool display_border_ = false;
 		TitleBlockTemplateRenderer *m_titleblock_template_renderer;
 };
 #endif