Fix -debug crash on windows caused by missing debug info for files.

core/os/os_windows.odin

@@ -322,4 +322,4 @@ is_windows_8_1 :: proc() -> bool {
 is_windows_10 :: proc() -> bool {
 	osvi := get_windows_version_ansi();
 	return (osvi.major_version == 10 && osvi.minor_version == 0);
-}
+}

src/ir.cpp

@@ -10028,7 +10028,11 @@ void ir_init_module(irModule *m, Checker *c) {
 
 	{
 		irDebugInfo *di = ir_alloc_debug_info(irDebugInfo_CompileUnit);
-		di->CompileUnit.file = m->info->files.entries[0].value; // Zeroth is the init file
+
+		GB_ASSERT(m->info->files.entries.count > 0);
+		AstFile *file = m->info->files.entries[0].value;
+
+		di->CompileUnit.file = file; // Zeroth is the init file
 		di->CompileUnit.producer = str_lit("odin");
 
 		map_set(&m->debug_info, hash_pointer(m), di);
@@ -10047,6 +10051,13 @@ void ir_init_module(irModule *m, Checker *c) {
 
 		array_init(&m->debug_location_stack, heap_allocator()); // TODO(lachsinc): ir_allocator() ??
 	}
+
+	{
+		for_array(i, m->info->files.entries) {
+			AstFile *file = m->info->files.entries[i].value;
+			ir_add_debug_info_file(m, file);
+		}
+	}
 }
 
 void ir_destroy_module(irModule *m) {

src/ir_print.cpp

@@ -2450,11 +2450,13 @@ void print_llvm_ir(irGen *ir) {
 
 		for_array(di_index, m->debug_info.entries) {
 			irDebugInfo *di = m->debug_info.entries[di_index].value;
+			GB_ASSERT_MSG(di != nullptr, "Invalid irDebugInfo");
 			ir_fprintf(f, "!%d = ", di->id);
-
 			switch (di->kind) {
 			case irDebugInfo_CompileUnit: {
-				irDebugInfo *file = *map_get(&m->debug_info, hash_pointer(di->CompileUnit.file));
+				irDebugInfo **found = map_get(&m->debug_info, hash_pointer(di->CompileUnit.file));
+				GB_ASSERT_MSG(found != nullptr, "Missing debug info for: %.*s\n", LIT(di->CompileUnit.file->fullpath));
+				irDebugInfo *file = *found;
 				ir_fprintf(f,
 				            "distinct !DICompileUnit("
 				              "language: DW_LANG_C_plus_plus" // Is this good enough?