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);
     }