Fixed tripple-fault when creating a new frame, after the current was gc'd.

We'll need to get rid of that awful VGA sometime soon.

sortix/vga.cpp

@@ -207,6 +207,7 @@ namespace Sortix
 		if ( process != NULL ) { ASSERT(CurrentProcess() == process); }
 		if ( userframe != NULL ) { Memory::UnmapUser((addr_t) userframe); Memory::InvalidatePage((addr_t) userframe); }
 		if ( physical != 0 ) { Page::Put(physical); }
+		if ( VGA::currentframe == this ) { VGA::currentframe = NULL; }
 	}
 
 	bool DevVGAFrame::IsType(unsigned type)

sortix/x86-family/memorymanagement.cpp

@@ -217,6 +217,8 @@ namespace Sortix
 			// Don't switch if we are already there.
 			if ( addrspace == currentdir ) { return currentdir; }
 
+			if ( addrspace & 0xFFFUL ) { PanicF("addrspace 0x%zx was not page-aligned!", addrspace); }
+
 			addr_t previous = currentdir;
 
 			// Switch and flush the TLB.