fix(go): support empty lists and strings

Signed-off-by: Roman Volosatovs <rvolosatovs@riseup.net>

Author: rvolosatovs

crates/wit-bindgen-go/src/interface.rs

@@ -477,6 +477,9 @@ impl InterfaceGenerator<'_> {
         }}
         if b < 0x80 {{
             x = x | uint32(b)<<s
+            if x == 0 {{
+                return "", nil
+            }}
             buf := make([]byte, x)
             {slog}.Debug("reading string bytes", "len", x)
             _, err = r.Read(buf)
@@ -515,11 +518,14 @@ impl InterfaceGenerator<'_> {
             }}
             return nil, {fmt}.Errorf("failed to read byte list length byte: %w", err)
         }}
+        if s == 28 && b > 0x0f {{
+            return nil, {errors}.New("byte list length overflows a 32-bit integer")
+        }}
         if b < 0x80 {{
-            if i == 4 && b > 1 {{
-                return nil, {errors}.New("byte list length overflows a 32-bit integer")
-            }}
             x = x | uint32(b)<<s
+            if x == 0 {{
+                return nil, nil
+            }}
             buf := make([]byte, x)
             {slog}.Debug("reading byte list contents", "len", x)
             _, err = {io}.ReadFull(r, buf)
@@ -562,11 +568,14 @@ impl InterfaceGenerator<'_> {
             }}
             return nil, {fmt}.Errorf("failed to read list length byte: %w", err)
         }}
+        if s == 28 && b > 0x0f {{
+            return nil, {errors}.New("list length overflows a 32-bit integer")
+        }}
         if b < 0x80 {{
-            if i == 4 && b > 1 {{
-                return nil, {errors}.New("list length overflows a 32-bit integer")
-            }}
             x = x | uint32(b)<<s
+            if x == 0 {{
+                return nil, nil
+            }}
             vs := make("#,
         );
         self.print_list(ty);