Improved error handling for struct types

src/types/ByName.go

@@ -8,7 +8,13 @@ import (
 func ByName(name string, pkg string, structs map[string]*Struct) Type {
 	if strings.HasPrefix(name, "*") {
 		to := strings.TrimPrefix(name, "*")
-		return &Pointer{To: ByName(to, pkg, structs)}
+		typ := ByName(to, pkg, structs)
+
+		if typ != nil {
+			return &Pointer{To: typ}
+		}
+
+		return nil
 	}
 
 	switch name {
@@ -32,5 +38,11 @@ func ByName(name string, pkg string, structs map[string]*Struct) Type {
 		return PointerAny
 	}
 
-	return structs[pkg+"."+name]
+	typ, exists := structs[pkg+"."+name]
+
+	if !exists {
+		return nil
+	}
+
+	return typ
 }