diff --git a/src/analyze.cpp b/src/analyze.cpp
index b6f08b7ae..bf7b6e363 100644
--- a/src/analyze.cpp
+++ b/src/analyze.cpp
@@ -543,6 +543,7 @@ TypeTableEntry *get_error_union_type(CodeGen *g, TypeTableEntry *err_set_type, T
         if (type_has_bits(err_set_type)) {
             entry->type_ref = err_set_type->type_ref;
             entry->di_type = err_set_type->di_type;
+            g->error_di_types.append(&entry->di_type);
         } else {
             entry->zero_bits = true;
             entry->di_type = g->builtin_types.entry_void->di_type;
diff --git a/src/codegen.cpp b/src/codegen.cpp
index 2f8ebf768..25c115b6f 100644
--- a/src/codegen.cpp
+++ b/src/codegen.cpp
@@ -4622,6 +4622,8 @@ static void validate_inline_fns(CodeGen *g) {
 static void do_code_gen(CodeGen *g) {
     assert(!g->errors.length);
 
+    codegen_add_time_event(g, "Code Generation");
+
     {
         // create debug type for error sets
         assert(g->err_enumerators.length == g->errors_by_index.length);
@@ -4644,8 +4646,6 @@ static void do_code_gen(CodeGen *g) {
         }
     }
 
-    codegen_add_time_event(g, "Code Generation");
-
     generate_error_name_table(g);
     generate_enum_name_tables(g);
 
diff --git a/std/os/child_process.zig b/std/os/child_process.zig
index 1b7639fb7..0b3040cdc 100644
--- a/std/os/child_process.zig
+++ b/std/os/child_process.zig
@@ -160,7 +160,7 @@ pub const ChildProcess = struct {
                 else => os.unexpectedErrorWindows(err),
             };
         }
-        self.waitUnwrappedWindows();
+        try self.waitUnwrappedWindows();
         return ??self.term;
     }
 
diff --git a/std/os/index.zig b/std/os/index.zig
index d8b230398..a2da2ec67 100644
--- a/std/os/index.zig
+++ b/std/os/index.zig
@@ -38,6 +38,7 @@ pub const windowsLoadDll = windows_util.windowsLoadDll;
 pub const windowsUnloadDll = windows_util.windowsUnloadDll; 
 pub const createWindowsEnvBlock = windows_util.createWindowsEnvBlock;
 
+pub const WindowsWaitError = windows_util.WaitError;
 pub const WindowsOpenError = windows_util.OpenError;
 pub const WindowsWriteError = windows_util.WriteError;
 
@@ -605,7 +606,9 @@ test "os.getCwd" {
     _ = getCwd(debug.global_allocator);
 }
 
-pub fn symLink(allocator: &Allocator, existing_path: []const u8, new_path: []const u8) !void {
+pub const SymLinkError = PosixSymLinkError || WindowsSymLinkError;
+
+pub fn symLink(allocator: &Allocator, existing_path: []const u8, new_path: []const u8) SymLinkError!void {
     if (is_windows) {
         return symLinkWindows(allocator, existing_path, new_path);
     } else {
@@ -613,7 +616,12 @@ pub fn symLink(allocator: &Allocator, existing_path: []const u8, new_path: []con
     }
 }
 
-pub fn symLinkWindows(allocator: &Allocator, existing_path: []const u8, new_path: []const u8) !void {
+pub const WindowsSymLinkError = error {
+    OutOfMemory,
+    Unexpected,
+};
+
+pub fn symLinkWindows(allocator: &Allocator, existing_path: []const u8, new_path: []const u8) WindowsSymLinkError!void {
     const existing_with_null = try cstr.addNullByte(allocator, existing_path);
     defer allocator.free(existing_with_null);
     const new_with_null = try cstr.addNullByte(allocator, new_path);
@@ -627,7 +635,23 @@ pub fn symLinkWindows(allocator: &Allocator, existing_path: []const u8, new_path
     }
 }
 
-pub fn symLinkPosix(allocator: &Allocator, existing_path: []const u8, new_path: []const u8) !void {
+pub const PosixSymLinkError = error {
+    OutOfMemory,
+    AccessDenied,
+    DiskQuota,
+    PathAlreadyExists,
+    FileSystem,
+    SymLinkLoop,
+    NameTooLong,
+    FileNotFound,
+    SystemResources,
+    NoSpaceLeft,
+    ReadOnlyFileSystem,
+    NotDir,
+    Unexpected,
+};
+
+pub fn symLinkPosix(allocator: &Allocator, existing_path: []const u8, new_path: []const u8) PosixSymLinkError!void {
     const full_buf = try allocator.alloc(u8, existing_path.len + new_path.len + 2);
     defer allocator.free(full_buf);
 
diff --git a/std/os/windows/util.zig b/std/os/windows/util.zig
index e2d7c1414..c19a5789e 100644
--- a/std/os/windows/util.zig
+++ b/std/os/windows/util.zig
@@ -7,7 +7,13 @@ const mem = std.mem;
 const BufMap = std.BufMap;
 const cstr = std.cstr;
 
-pub fn windowsWaitSingle(handle: windows.HANDLE, milliseconds: windows.DWORD) !void {
+pub const WaitError = error {
+    WaitAbandoned,
+    WaitTimeOut,
+    Unexpected,
+};
+
+pub fn windowsWaitSingle(handle: windows.HANDLE, milliseconds: windows.DWORD) WaitError!void {
     const result = windows.WaitForSingleObject(handle, milliseconds);
     return switch (result) {
         windows.WAIT_ABANDONED => error.WaitAbandoned,