From 4f211efe89c3d86073369fc4b609ec8498aa61db Mon Sep 17 00:00:00 2001
From: Michael Williamson <mike@zwobble.org>
Date: Fri, 19 Jun 2026 17:48:16 +0100
Subject: Handle unknown namespace in import type checking

---
 .../org/zwobble/hobgoblin/compiler/typechecker/TypeChecker.java    | 4 +++-
 .../hobgoblin/compiler/typechecker/TypeCheckerGlobalContext.java   | 5 ++---
 .../hobgoblin/compiler/typechecker/UnknownNamespaceError.java      | 7 +++++++
 3 files changed, 12 insertions(+), 4 deletions(-)

(limited to 'src/main')

diff --git a/src/main/java/org/zwobble/hobgoblin/compiler/typechecker/TypeChecker.java b/src/main/java/org/zwobble/hobgoblin/compiler/typechecker/TypeChecker.java
index 78bdc97..384ef19 100644
--- a/src/main/java/org/zwobble/hobgoblin/compiler/typechecker/TypeChecker.java
+++ b/src/main/java/org/zwobble/hobgoblin/compiler/typechecker/TypeChecker.java
@@ -29,7 +29,9 @@ public class TypeChecker {
                 untypedImport.source()
             );
 
-            var importedNamespaceFields = context.namespaceFields(importedNamespace);
+            var importedNamespaceFields = context.namespaceFields(importedNamespace)
+                .orElseThrow(() -> new UnknownNamespaceError(importedNamespace, untypedImport.source()));
+
             for (var importedName : untypedImport.importedNames()) {
                 var fieldType = importedNamespaceFields.fieldType(importedName)
                     .orElseThrow(() -> new UnknownNamespaceFieldError(
diff --git a/src/main/java/org/zwobble/hobgoblin/compiler/typechecker/TypeCheckerGlobalContext.java b/src/main/java/org/zwobble/hobgoblin/compiler/typechecker/TypeCheckerGlobalContext.java
index e50e424..ff6cd5e 100644
--- a/src/main/java/org/zwobble/hobgoblin/compiler/typechecker/TypeCheckerGlobalContext.java
+++ b/src/main/java/org/zwobble/hobgoblin/compiler/typechecker/TypeCheckerGlobalContext.java
@@ -43,8 +43,7 @@ public class TypeCheckerGlobalContext {
         this.namespaceFieldsOf.put(namespaceName, new Fields(fields));
     }
 
-    public Fields namespaceFields(NamespaceName namespaceName) {
-        // TODO: better error handling
-        return Optional.ofNullable(namespaceFieldsOf.get(namespaceName)).orElseThrow();
+    public Optional<Fields> namespaceFields(NamespaceName namespaceName) {
+        return Optional.ofNullable(namespaceFieldsOf.get(namespaceName));
     }
 }
diff --git a/src/main/java/org/zwobble/hobgoblin/compiler/typechecker/UnknownNamespaceError.java b/src/main/java/org/zwobble/hobgoblin/compiler/typechecker/UnknownNamespaceError.java
index fb06f3b..1ca4ac7 100644
--- a/src/main/java/org/zwobble/hobgoblin/compiler/typechecker/UnknownNamespaceError.java
+++ b/src/main/java/org/zwobble/hobgoblin/compiler/typechecker/UnknownNamespaceError.java
@@ -5,7 +5,14 @@ import org.zwobble.hobgoblin.compiler.sources.Source;
 import org.zwobble.hobgoblin.compiler.types.NamespaceName;
 
 public class UnknownNamespaceError extends SourceError {
+    private final NamespaceName namespaceName;
+
     public UnknownNamespaceError(NamespaceName namespaceName, Source source) {
         super("Unknown namespace: " + namespaceName, source);
+        this.namespaceName = namespaceName;
+    }
+
+    public NamespaceName namespaceName() {
+        return namespaceName;
     }
 }
-- 
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