TD: [skip ci] Fix coverity warning

Coverity warnings fixed:

CID 316559 (#1 of 1): Uninitialized scalar variable (UNINIT)
3. uninit_use_in_call: Using uninitialized value we. Field we.idx is uninitialized when calling push_back

CID 316549 (#1 of 1): Uninitialized scalar field (UNINIT_CTOR)
4. uninit_member: Non-static class member pageheight is not initialized in this constructor nor in any functions that it calls.

CID 186161 (#1 of 1): Uninitialized pointer field (UNINIT_CTOR)
2. uninit_member: Non-static class member parent is not initialized in this constructor nor in any functions that it calls.

CID 305170 (#1 of 1): Dereference before null check (REVERSE_INULL)
check_after_deref: Null-checking this->m_baseFeat suggests that it may be null, but it has already been dereferenced on all paths leading to the check.

CID 186152 (#2 of 2): Uninitialized pointer field (UNINIT_CTOR)
3. uninit_member: Non-static class member m_mdi is not initialized in this constructor nor in any functions that it calls.

CID 192588 (#1 of 1): Same on both sides (CONSTANT_EXPRESSION_RESULT)
pointless_expression

src/Mod/TechDraw/App/EdgeWalker.cpp

@@ -343,6 +343,7 @@ std::vector<WalkerEdge> EdgeWalker::makeWalkerEdges(std::vector<TopoDS_Edge> edg
         WalkerEdge we;
         we.v1 = v1dx;
         we.v2 = v2dx;
+        we.idx = 0;
         walkerEdges.push_back(we);
     }
 

src/Mod/TechDraw/Gui/MDIViewPage.cpp

@@ -124,6 +124,8 @@ MDIViewPage::MDIViewPage(ViewProviderPage *pageVp, Gui::Document* doc, QWidget*
     m_orientation(QPrinter::Landscape),
     m_paperSize(QPrinter::A4),
 #endif
+    pagewidth(0.0),
+    pageheight(0.0),
     m_vpPage(pageVp)
 {
 

src/Mod/TechDraw/Gui/QGIViewDimension.cpp

@@ -100,6 +100,8 @@ QGIDatumLabel::QGIDatumLabel()
     posX = 0;
     posY = 0;
 
+    parent = nullptr;
+
     setCacheMode(QGraphicsItem::NoCache);
     setFlag(ItemSendsGeometryChanges, true);
     setFlag(ItemIsMovable, true);

src/Mod/TechDraw/Gui/TaskLeaderLine.cpp

@@ -402,8 +402,10 @@ void TaskLeaderLine::createLeaderFeature(std::vector<Base::Vector3d> converted)
                        m_leaderType.c_str(),m_leaderName.c_str());
     Command::doCommand(Command::Doc,"App.activeDocument().%s.addView(App.activeDocument().%s)",
                        PageName.c_str(),m_leaderName.c_str());
-    Command::doCommand(Command::Doc,"App.activeDocument().%s.LeaderParent = App.activeDocument().%s",
-                           m_leaderName.c_str(),m_baseFeat->getNameInDocument());
+    if (m_baseFeat != nullptr) {
+        Command::doCommand(Command::Doc,"App.activeDocument().%s.LeaderParent = App.activeDocument().%s",
+                               m_leaderName.c_str(),m_baseFeat->getNameInDocument());
+    }
 
     App::DocumentObject* obj = m_basePage->getDocument()->getObject(m_leaderName.c_str());
     if (obj == nullptr) {

src/Mod/TechDraw/Gui/TaskRichAnno.cpp

@@ -76,6 +76,7 @@ using namespace TechDrawGui;
 TaskRichAnno::TaskRichAnno(TechDrawGui::ViewProviderRichAnno* annoVP) :
     ui(new Ui_TaskRichAnno),
     blockUpdate(false),
+    m_mdi(nullptr),
     m_view(nullptr),
     m_annoVP(annoVP),
     m_baseFeat(nullptr),

src/Mod/TechDraw/TDTest/DVBalloonTest.py

@@ -76,7 +76,7 @@ def DVBalloonTest():
     FreeCAD.ActiveDocument.recompute()
 
     rc = False
-    if ("Up-to-date" in balloon2.State) and ("Up-to-date" in balloon2.State):
+    if ("Up-to-date" in balloon1.State) and ("Up-to-date" in balloon2.State):
         rc = True
     FreeCAD.closeDocument("TDBalloon")
     return rc