Fix save so it doesn't try to save to "/blank" when you pass that parameter.

Author: fdwr

Common.String.ixx

@@ -141,10 +141,17 @@ void TrimSpaces(_Inout_ std::u16string& text)
 
 void UnquoteString(_Inout_ std::u16string& path)
 {
+    if (path.empty())
+        return;
+
     if (path.back() == '\"')
     {
         path.pop_back();
     }
+
+    if (path.empty())
+        return;
+
     if (path.front() == '\"')
     {
         path.erase(0, 1);

MainWindow.ixx

@@ -116,6 +116,7 @@ int APIENTRY wWinMain(
         else if (_wcsicmp(ToWChar(trimmedCommandLine.c_str()), L"/blank") == 0)
         {
             wantBlankCanvas = true;
+            trimmedCommandLine.clear();
         }
         else if (trimmedCommandLine[0] == '/')
         {